UC-NRLF 


TESTING  &  WORKING 

SILVER  ORES 


CHAS.    H.    AARON 


Wo. 

Division 

Range 

Shelf. 

Received. 


University  of  California. 


C-J-IF"!'    OF1 


A  PRACTICAL  TREATISE 


TESTING  AND  WORKING 


ORES. 


BY    CHAS.    H.    AARON. 
1  * 

L  I  H  K  A  II  \ 

. 

UNIVERSITY    OF 

•     jj 

PUBLISHED'  AND  %OLD  iv  DEw'kT  &  XX)V  * 

Proprietors  of  the  MINING  AND  SCIENTIFIC  PRESS,  San  Francisco,  Cal. 
1876. 


Entered  according  to  Act  of  Congress,  in  the  office  of  the  Librarian  of 
Congress,  at  Washington,  D.  C.,  in  the  year  1876,  by 

CHAS.  H.  AARON  and  DEWEY  &  Co. 
^^/  J  o  -L    „ 


Printed  by  SPAULDING  &  BARTO, 
414  Clay  St.,  San  Francisco. 


X 


LIBRA  U  Y 

UNIVERSITY   (>!• 

CALIFORNIA. 


PREFACE. 


In  1869,  I  wrote  a  little  pamphlet  on  amalgama- 
tion of  silver  ores,  in  which  was  set  forth  a  method 
of  treatment  by  which  certain  ores  of  silver  usual- 
ly considered  refractory,  could  be  worked  to  90 
per  cent,  of  the  assay  without  roasting.  I  shortly 
afterward  introduced  that  method  at  Benton,  in 
Mono  County,  with  such  success  that  two  mills, 
of  ten  and  five  stamps,  respectively,  have  since 
been  built  to  work  it,  in  each  case  with  excellent 
results. 

I  myself  worked  the  process  for  several  years, 
with  no  better  crushing  machinery  than  an  arastra, 
which,  with  an  amalgamating  barrel  and  separator 
(the  whole  driven  by  a  water-wheel)  formed  a  cheap 
and  efficient  mill  for  the  purpose,  though  better 
adapted  to  the  use  of  a  person  having  a  mine  of 
his  own,  than  for  custom  work. 

A  large  portion  of  the  matter  of  my  pamphlet, 
which  was  sold  for  25  cents  per  copy,  has  lately 
been  published,  in  a  slightly  garbled  form,  as  a 
circular,  with  the  title  of  ' '  Instructions  for  testing 
and  milling  ores/' by  one  N.  L.  Turner,  in  Mon- 
tana Territory,  being  put  forth  as  Mr.  Turner's 


4  PREFACE. 

own  production,  and  sold,  as  I  am  informed,  at 
the  very  modest  price  of  ten  dollars  per  copy. 

In  addition  to  the  matter  taken  from  my  pamph- 
let, this  circular  contains  sundry  passages  from 
articles  written  by  me,  and  published  in  the  MIN- 
ING AND  SCIENTIFIC  PRESS,  showing  that  Mr.  Turner 
has  been  a  diligent  and  appreciative  reader  of  my 
writings,  and  I  must  give  give  him  credit  for  hav- 
ing been  so  much  smarter  than  myself,  that  if  he 
has  sold  even  a  few  copies  at  ten  dollars  each,  he 
has  made  more  out  of  them  than  I  ever  did. 

Since  writing  the  pamphlet,  I  have  had  five 
years  experience  and  observation  of  the  process 
therein  described,  and  as  my  profit  has  consisted 
in  part  of  the  additional  knowledge  thus  gained,  I 
now  propose  to  offer  to  the  mining  public,  more 
and  better  information  than  is  contained  in  that, 
or  in  Mr.  Turner's  piratical  circular,  adding  also 
some  information  and  suggestions  in  regard  to 
other  processes. 

I  do  not  write  for  students  of  science,  nor  to 
make  a  display  of  learning,  which,  for  all  the  read- 
er would  know,  might  or  might  not  be  "all  out  of 
my  own  head."  My  aim  is  simply  to  contribute  my 
quota  to  the  diffusion  of  practical  knowledge  of 
some  matters  pertaining  to  the  development  of 
silver  mining,  and  to  make  certain  suggestions,  of 
the  value  of  which  I  leave  the  reader  to  judge. 

I  shall,  then,  try  to  write  so  as  to  be  understood 
by  common  miners  and  prospectors,  and  what  I 


PEEEACE.  5 

say  will  be  chiefly  the  result  of  my  own  experience 
and  my  own  thought;  not  stereotyped  matter  which 
may  be  found  in  a  dozen  works  on  Metallurgy  in 
any  of  our  libraries. 

In  all  silver  regions  there  is  found  more  or  less 
silver  ore  in  the  form  of  small  veins,  or  threads  as 
the  Mexicans  say,  or  in  bunches,  pockets  and  de- 
posits of  little  extent,  which,  while  they  will  not 
justify  the  attention  of  capitalists,  might  yet  fur- 
nish profitable  occupation  to  a  number  of  miners, 
if  the  owners  only  had  sufficient  knowledge  to  ex- 
tract the  silver  in  a  cheap  and  simple  way. 

This  wrant  is  partly  met  by  custom  mills,  but 
aside  from  the  fact  that  miners  generally  have  a 
strong  impression  that  they  are  very  often  swin- 
dled at  those  places,  it  often  happens  that  the 
small  and  rich  mines  spoken  of  are  quite  remote 
from  any  mill. 

In  the  mineral  districts  of  Mexico,  nearly  every 
miner  has  some  knowledge,  however  rude,  of  met- 
allurgical operations,  which  enables  him  to  work, 
in  one  way  or  other,  any  small  rich  "hilo"  which 
he  may  discover,  and  though  in  large  operations 
the  Mexicans  may  not  be  able  to  compete  with 
more  enterprising  people,  yet  it  is  a  fact,  that 
among  miners  and  prospectors,  a  Mexican  will 
make  a  good  living  where  an  American  would 
starve  to  death. 

Though  I  write  mainly  for  the  benefit  of  the 
poor  and  unlearned  class  in  our  mining  districts, 


0  PREFACE. 

it  must  not  be  supposed  that  the  methods  of  which 

1  treat  are  not  adapted  to  large  operations;  on  the 
contrary,  if  my  modification  of  the  old  "  Fond  on" 
of  Alonzo  Barba  had  been  adopted  for  the  Corn- 
stock   mines  long  ago,  many  millions  of   dollars 
which  are  now  in  the  Carson  river,  might  be  in  the 
pockets  of  stockholders,  and  the  value  of   stocks 
would  be  proportionally  higher.      I  do  not  mean 
to  say  that  I  am  the  only  man  who  could  have  done 
this,  but  I  speak  for  myself,  and  others  have  the 
same  privilege. 

If  it  be  asked  why  I  have  not  tried  to  introduce 
my  process  at  Virginia,  I  can  only  say  that  I  have 
not  kept  the  matter  secret,  and  it  is  the  business 
of  those  interested  to  see  to  the  working  of  their 
ores  in  the  best  manner. 

I  have  to  presuppose  a  certain  amount  of  knowl- 
edge on  the  part  of  the  reader,  in  regard  to  the 
general  operations  of  milling;  for  to  go  into  all  the 
details  of  feeding  battery,  charging  pans  or  bar- 
rels, cleaning  up,  pressing  amalgam,  retorting,  etc. 
would  carry  me  far  beyond  my  proposed  limit. 
Most  men  in  the  mines  either  have,  or  can  easily 
acquire,  such  knowledge,  and  my  object  is  to  en- 
able them  to  use  it  for  their  own  benefit,  while  at 
the  same  time  offering  some  suggestions  to  persons 
of  more  advanced  pretentious  who  may  choose  to 
avail  themselves  thereof. 

C.  H.  AAEON. 


TESTING  ORES  FOR  SILVER. 


[1.]  I  shall  not  attempt  to  give  any  instructions 
as  to  the  geological  or  lithological  formations 
in  which  the  discovery  of  silver  may  be  expected, 
for  several  reasons.  In  the  first  place,  such  knowl- 
edge as  we  have  on  this  subject,  may  be  obtained 
from  many  standard  works;  in  the  second  place,  it 
is  not  very  easliy  applied  when  obtained,  as,  aside 
from  the  difficulty  of  at  once  determining  the  char- 
acter of  rock  formation,  a  region  consisting  mainly 
of  non-metalliferous  rock,  which  might  discourage 
a  learned  person  from  searching,  may  nevertheless 
contain  within  it  a  tract  rich  in  metals;  and  in  the 
third  place,  such  knowledge  is  not  altogether  reli- 
able, nor  is  the  ordinary  prospector  qualified  to 
avail  himself  of  it,  or  indeed  likely  to  be  guided 
by  anything  but  his  own  notions,  derived  from  his 
own,  or  his  friends'  experience. 

I  shall,  then,  suppose  that  the  seeker  after  min- 
eral wealth,  having  journeyed  at  his  "  own  sweet 


8  TESTING   AND    WORKING 

will"  over  desert  valley  and  rugged  mountain, has 
at  last  found  a  vein  of  ore,  or  at  least  some  "rich 
looking  float,"  and  having  brought  a  sample  down 
to  his  camp  by  the  spring,  is  anxious  to  know,  be- 
fore going  further,  whether  the  "queer  looking 
stuff "  contains  silver,  or  only  a  base  conglomera- 
tion of,  to  him,  worthless  metals. 

Now,  I  am  not  going  to  afflict  this  innocent  and 
much  suffering  prospector  with  scientific  details, 
touching  the  crystalline  form,  chemical  composi- 
tion, fracture,  streak,  and  specific  gravity  of  the 
many  different  ores  of  silver,  or  minerals  which 
carry  more  or  less  silver,  in  regard  to  which  partic- 
ulars he  is  most  likely  either  profoundly  indifferent, 
or  profanely  contemptuous.  All  he  wants  to  know, 
for  the  present  at  least,  is  whether  or  not  the  ore 
contains  silver,  which  he  may  ascertain  with  cer- 
tainty by  proceeding  as  follows: 

[2.]  Grind  a  few  ounces  of  the  ore  to  powder 
between  two  rocks;  add  to  it  about  one-tenth  as 
much  salt  and  about  half  that  quantity  of  sulphate 
of  iron,  often  called  copperas j  mix  all  together, 
and  put  it  into  an  old  shovel  or  frying  pan,  which 
should  have  been  previously  smeared  with  clay  or 


SILVEK    OEES. 


9 


mud,  and  dried;  then  roast  it  over  a  fire,  lyeiug 
careful  to  stir  it  often  with  a  piece  of  stout  iron 
wire.  Let  the  roasting  proceed  quite  gently  so 
long  as  a  smell  of  burning  sulphur  can  be  per- 
cevied,  not  allowing  the  heat  to  exceed  a  dark  red  as 
seen  at  night.  When  the  fumes  of  sulphur  cease, 
let  the  heat  increase  to  a  rather  light  red,  but  not 
so  as  to  melt  the  'ore,  stirring  it  still  with  the  wire. 
The  smell  will  now  be  that  of  chlorides,  rather 
pungent,  often  sweet  as  of  new  hay,  but  very  easily 
distinguished  from  that  of  sulphur.  The  ore  will 
swell,  and  appear  woolly  and  somewhat  sticky,  and 
a  few  minutes  of  this  hotter  roasting  will  finish  it 
well  enough  for  your  purpose.  Now  transfer  the 
roasted  ore  to  a  flat  rock  and  let  it  cool;  add  a  lit- 
tle more  salt,  and  enough  water  to  make  it  like 
mortar;  imbed  in  the  mass  a  strip  of  clean  sheet 
copper,  and  let  it  remain  ten  minutes;  take  the 
copper  out,  and  without  touching  the  part  that  has 
been  in  the  pulp,  wash  the  mud  off  it  with  clean 
water.  If  the  ore  contains  silver,  it  will  invariably 
show  as  a  white  coating  on  the  copper,  and  as  no 
other  metal  will  so  coat  the  copper  under  these 
conditions,  the  appearance  of  such  a  coating  is 
proof  positive  of  the  presence  of  silver.  The  white 
1* 


10  TESTING   AND    WORKING 

coating  will  be  heavier  or  lighter  according  to  the 
richness  of  the  ore,  if  very  heavy  it  will  appear 
grey  and  rough. 

For  making  the  above  test  you  will  require — 
Salt, 

Sulphate  of  Iron, 
An  old  shovel  or  frying  pan, 
A  piece  of  stout  iron  wire, 
*A  strip  of  sheet  copper  six  inches  long, 
By  making  a  few  tests  in   this   way   with   ore 
which  _is  known  to  contain  silver,  confidence  will 
be  acquired. 

The  Sulphate  of  Iron  is  not  required  if  the  ore 
contains  sulphurets,  but  as  you  may  possibly  be 
deceived  on  this  point  by  substances  resembling 
sulphurets,  it  is  best  4to  make  sure  by  using  it  in 
every  case, 

[3.  ]  Many,  in  fact  most  silver  ores,  will  indicate 
the  presence  of  silver  by  simply  mixing  about  an 
ounce  with  boiling  water,  salt  and  a  little  bluestone, 
in  a  teacup,  and  placing  the  strip  of  copper  in  it  for 
a  few  minutes,  while  keeping  it  at  a  boiling  heat; 
and  as  this  is  simpler  than  the  roasting,  it  is  well 
to  try  it  first.  If  the  copper  becomes  whitened 


SILVER   ORES.  11 

you  may  be  sure  you  have  silver,  unless  indeed,  it 
should  be  quicksilver,  which  however,  you  will 
hardly  meet  with  in  the  silver  regions,  and  which 
is  easily  known  by  slightly  heating  the  copper  in 
the  fire,  when  quicksilver  will  be  driven  off,  but 
silver  will  not.  Most  miners  will  find  no  difficulty 
in  distinguishing  between  the  two  by  simply  rub- 
bing with  the  finger. 

For  this  test  you  will  require — 

Salt, 

Bluestone, 

A  strip  of  Copper  and 

A  teacup, 

or  a  basin  which  can  be  set  in  the  top  of  an  empty 
oyster  can,  in  which  a  little  water  is  kept  boiling, 
so  that  the  basin  with  its  contents  is  kept  hot.  I 
have  tried  this  test  with  many  samples  of  silver 
ore,  and  it  has  never  failed,  yet  the  first  one  is  still 
more  certain. 

[4.]  Some  prospectors  test  ore  by  heating  a 
small  piece  red  hot,  and  then  plunging  it  into 
water,  when  the  more  fusible  metals  it  may  con- 
tain appear  on  the  surface  in  the  form  of  globules, 
method  is  not  reliable,  because  other  met- 


12  TESTING   AND   WORKING 

als  besides  silver  may  show  themselves,  and  either 
be  mistaken  for  silver  where  it  does  not  exist,  or 
disguise  it  where  it  does. 

[5.]  The  most  generally  known  method  of  test- 
ing for  silver,  is  by  acting  upon  a  little  ore  powder 
in  a  test  tube  with  nitric  acid,  and  adding  salt  to 
the  clear  solution  thus  formed;  if  silver  is  present 
it  appears  as  a  more  or  less  dense  white  cloud,  or, 
if  in  very  small  quantity,  as  a  slight  milkiness  in 
the  acid.  This  method  is  open  to  two  objections. 
In  the  first  place,  some  of  the  richest  ores  of  silver 
are  not  acted  on  by  nitric  acid,  and  would  there- 
fore show  no  sign  on  addition  of  salt;  and  in  the 
second  place,  lead  gives  the  same  appearance  as 
silver,  as  does  also  quicksilver,  and  though  an  ex- 
pert would  easily  distinguish  one  from  the  other,  by 
further  tests,  yet  these  defects  render  the  method 
unsuitable  for  the  common  prospector,  be- 
sides which,  nitric  acid  is  not  a  very  nice  thing  to 
pack  with  provisions  and  blankets,  nor  to  handle 
in  the  desert. 

[6.]  I  say  nothing  about  the  test  with  the  blow- 
pipe, because,  though  extremely  valuable  in  the 


SILVER   ORES.  13 

hands  of  an  expert,  the  use  of  this  instrument  re- 
quires great  practice,  and  considerable  skill  in 
manipulation,  and  the  big  fingers  of  miners  do  not 
take  kindly  to  such  delicate  work.  Nor  do  I  de- 
scribe the  usual  methods  of  fire  assay,  because 
they  require  an  outfit  which  could  not  well  be  car- 
ried about  by  the  prospector;  nor  are  these  things 
necessary  till  it  is  required  to  know  the  richness  of 
the  ore,  when  it  is  best  to  apply  to  a  regular  assay- 
er,  though,  when  it  comes  to  that,  the  blowpipe 
assay  of  a  carefully  taken  sample,  or  of  mere  spec- 
imens, is  quite  accurate  enough,  if  well  made,  for 
all  the  purposes  of  the  prospector,  or  for  assorting 
ores,  and  as  it  costs  a  mere  trifle,  I  think  assay- 
ers  ought  to  use  it  more  than  they  do,  as  a  cheap 
and  lucrative  method  of  supplying  the  wants  of 
poor  laboring  men,  who  merely  require  to  know 
approximately,  the  value  of  their  ore.  I  have 
made  hundreds  of  these  assays  for  fifty  cents  each 
in  the  mines,  as  it  takes  only  from  fifteen  to  twenty 
minutes  to  make  one. 


I  UNIVERSITY  OF  | 

<'AUF()j>XiA.    I 

X 


TESTING  FOR  A  PROCESS. 


[7.]  When  ore  has  been  found,  which,  by  eith- 
er of  the  foregoing  tests,  gives  evidence  of  contain- 
ing silver,  it  will  be  well  to  make  some  explora- 
tion to  ascertain  if  it  exists  in  considerable  quan- 
tity, in  which  case  a  few  fair  samples  should  be 
taken  to  a  reliable  assayer  in  order  that  its  richness 
may  be  known. 

If  the  ore  is  very  rich,  it  will,  of  course,  bear 
transportation  to  a  market;  yet  the  losses,  expenses 
and  discounts  which  are  inseparable  from  this  way 
of  disposing  of  it,  not  to  mention  the  trouble  and 
risk  of  fraud,  have  caused  miners  in  general  to  en- 
tertain a  strong,  and  not  unfounded  objection  to 
selling  their  ore,  especially  when  the  market  is 
very  distant;  besides  which,  the  quantity  of  such 
ore  is  usually  quite  small,  though  there  may  be 
considerable  of  a  grade  which  would  pay  quite 
well  to  work  in  a  small  mill  near  the  mine,  and 
owned  by  the  miner. 


SILVER   OEES.  15 

Of  course  large  mills  work  more  cheaply,in  pro- 
portion, provided  they  are  fully  supplied  with  ore; 
but  a  man  who  has  only  a  small  mine  must  be  con- 
tent with  a  small  mill,  and  as  the  extraction  of  ore 
also  costs  more  in  this  case,  the  profitable  limit  of 
value  will  be  higher  than  when  the  mine  and  mill 
are  large,  and  must  be  decided  according  to  cir- 
cumstances. But  whether  the  mill  is  to  be  large 
or  small,  it  is  equally  necessary  to  find  out,  before 
building  it,  whether  the  ore  can  be  worked  raw,  or 
must  be  roasted  or  smelted. 

[8.]  If  fuel  is  abundant,  smelting  is  preferable 
when  the  ore  contains  a  large  percentage  of  lead, 
and  becomes  indispensable  if  the  quantity  is  exces- 
sive. However,  ore  containing  as  much  as  thirty 
per  cent,  of  lead  can  be  worked  by  roasting.  If 
not  necessarily  a  smelting  ore,  it  remains  *to  be 
seen  whether  it  can  be  worked  without  roasting  or 
not,  which  can  be  ascertained  as  follows,  so  far  at 
least  as  processes  which  I  can  recommend  to  un- 
learned persons  are  concerned : 

[9.]  A  fair  average  sample  is  taken  and  reduced 
to  powder,  fine  enough  to  pass  through  at  least  a 


16  TESTING   AND    WOKKING 

40-mesh  wire  gauze.  If,  however,  the  sample  is 
large,  it  will  suffice  if  it  be  crushed  coarsely  at 
first,  then,  after  thorough  mixing,  spread  upon  a 
smooth  floor  and  halved;  one-half  being  rejected, 
the  other  is  crushed  finer  and  again  mixed  and 
halved,  and  so  on  until  the  last  half  equals  about 
six  pounds,  which  is  all  passed  through  a  fine  sieve, 
Of  this  fine  pulp,  again  well  mixed,  five  pounds 
are  carefully  weighed  for  a  working  sample,  and 
the  remainder  set  aside  for  an  assay. 

[10.]  The  working  sample  is  put  into  a  porce- 
lain-lined iron  kettle,  such  as  are  used  in  a  mill  for 
carrying  quicksilver;  water  enough  to  form  a  thin 
pulp,  and  two  or  more  ounces  of  salt  are  added. 
The  pot  is  then  put  on  a  stove  or  over  a  fire,  and 
heated  to  boiling  of  the  pulp,  while  stirred  with  a 
strip  o*f  wood  to  prevent  the  ore  from  settling  to 
the  bottom,  which  would  cause  the  destruction  of 
the  enamel.  When  hot,  a  little  strong  solution  of 
bluestone  is  added  to  the  pulp,  and  a  piece  of 
sheet  copper  about  five  inches  square,  or  several 
smaller  pieces,  together  with  about  four  ounces  of 
quicksilver,  are  also  put  in.  As  the  pulp  will  grad- 
ually dry  by  evaporation,  hot  water  is  added  from 


SILVER   ORES.  17 

time  to  time,  and  the  whole  is  frequently  stirred 
with  the  strip  of  wood. 

After  from  five  to  ten  minutes,  a  clean  strip  of 
iron,  or  the  blade  of  a  case  knife,  is  dipped  into  the 
pulp  for  a  few  seconds,  then  washed,  without  rub- 
bing, in  clean  water;  it  should  show  a  pretty  strong 
color  of  copper;  if  it  does  not,  more  solution  of 
bluestone  is  added  to  the  pulp,  and  the  trial  re- 
peated, and  so  on  till  the  iron  becomes  coated 
with  copper,  when  it  is  known  that  enough  blue- 
stone  has  been  used;  the  heat  and  stirring  are  con- 
tinued, the  sheet  copper  in  the  pot  being  pushed 
about  through  the  pulp. 

It  is  absolutely  necessary  that  there  be  copper 
in  solution  in  the  pulp,  and  as  there  may  be  in  the 
ore  some  substance  which  will  destroy  a  quantity 
of  the  bluestone  used,  it  is  best  to  repeat  the  test 
with  the  knife  blade  once  or  twice  more,  adding 
bluestone  if  necessary,  till  it  is  found  that  a  per- 
manent reaction  of  copper  is  established;  but  the 
stirring  must  be  done  with  a  stick,  not  with  the 
iron  knife,  as  that  is  only  used  as  a  test  to  show  if 
the  pulp  is  in  proper  condition.  The  continued 
presence  of  iron  would  ruin  the  experiment. 

After  a  short  time  the  pieces  of  sheet  copper  will 


18  TESTING   AND   WORKING 

become  coated  with  quicksilver,  and  will  appear 
rough  on  the  surface,  from  adhesion  of  silver  amal- 
gam and  corrosion  of  the  copper,  and  particles  of 
ore  are  seen  to  adhere  slightly  to  the  copper  and 
to  the  quicksilver,  and  this,  whether  in  the  test  or 
in  the  large  working,  is  an  indication  that  the  op- 
eration is  proceeding  favorably,  while  the  cessation 
of  the  phenomenon  is  an  indication  of  its  comple- 
tion. 

The  operation  is  continued  till  a  clean  strip  of 
copper  dipped  into  the  hot  pulp  for  several  min- 
utes, comes  out  perfectly  free  from  a  white  deposit 
of  silver,  which  may  require  from  three  to  ten 
hours. 

[11.]  When  about  to  use  the  copper  test,  the 
pulp  is  made  rather  thin,  by  the  addition  of  hot 
water,  to  allow  the  quicksilver  to  settle  to  the  bot- 
tom, and  care  must  be  used  not  to  touch  it  with 
the  copper.  If,  notwithstanding  all  precautions, 
the  copper  should  appear  spotted  with  quicksilver, 
it  must  be  heated  in  the  fire,  scoured  clean,  and  the 
trial  repeated.  The  iron  test  is  used  at  the  same 
time,  to  make  sure  that  the  pulp  is  in  the  proper 
condition,  that  is,  that  it  contains  .a  solution  of 
copper. 


SILVER    OKES.  19 

In  commencing  this  operation,  it  Some- 
times happens  that  the  iron  tester  is  blackened,  in- 
stead of  being  coppered;  in  this  case  the  work  is 
continued  some  little  time  without  addition  of 
more  bluestone,  when,  on  repeating  the  trial,  the 
proper  effect  will  usually  be  got. 

[12.  J  In  order  to  know  how  much  bluestone 
has  been  used,  it  is  best,  before  beginning,  to 
weigh  two  ounces,  and  put  it  into  a  bottle  which 
will  hold  enough  water  to  dissolve  it,  adding  one 
ounce  of  salt,  and  filling  the  bottle  with  water. 
If,  at  the  end  of  the  operation,  the  bottle  is  half 
emptied,  it  is  clear  that  one  ounce  of  the  blue- 
stone  has  been  used,  and  so  in  proportion  for  less 
quantities.  It  is  important  to  know  how  much  blue- 
stone  has  been  used,  as  calculation  may  then  be 
made  of  the  expense  of  working  on  the  large  scale; 
thus,  if  5  Ibs.,  or  80  ounces  of  ore  consumes  0.5oz. 
of  bluestone,  then  one  ton,  or  2,000  Ibs.,  will  re- 
quire— 

80: 0.5::  2000: 12.5  pounds. 

Some  ores  require  more,  but  the  Comstock  ore 
works  well  with  4  pounds  to  the  ton.  The  salt 
used  on  the  large  scale  will  be  from  50  to  100  Ibs. 


20  TESTING   AND   WORKING 

to  the  ton  of  ore,  and  in  addition,  one-half  the 
weight  of  the  bluestone. 

[13.]  When  the  strip  of  copper  shows  that  no 
more  silver  can  be  got,  although  the  pulp  is  boil- 
ing hot,  and  the  case  knife  shows  the  contin- 
ued presence  of  a  solution  of  copper,  the  adhering 
amalgam  is  removed  from  the  sheet  copper,  by 
stripping  it  between  the  fingers  and  thumb,  the 
pulp  is  "panned  out"  of  the  pot,  and  the  amal- 
gam strained  out  of  the  quicksilver  with  a  piece  of 
buckskin  or  wet  drilling.  The  ball  of  amalgam 
thus  obtained,  which  will  be  white  and  crisp,  is 
tied  up  in  a  piece  of  rag,  and  placed  in  an  assay 
crucible,  or  any  vessel  which  will  stand  heat,  and 
is  slowly  heated  to  redness.  After  cooling,  the 
spongy  silver  is  assayed  to  ascertain  its  value, 
which,  multiplied  by  400,  gives  the  amount  per  ton 
that  the  ore  will  yield.  If  the  silver  is  clean,  as  it 
ought  to  be  when  worked  in  this  way,  it  may  be 
estimated,  without  assaying,  at  $1.25  per  Troy 
ounce. 

For  making  this  test,  the  following  appliances 
are  required — 

A  pestle  and  mortar  (or  a  flat  rock  and  small 
boulder) ; 


SILVER  ORES.  21 

A  sieve  of  at  least  40  meshes  to  the  linear  inch ; 

A  porcelain-lined  kettle; 

A  strip  of  sheet  copper,  and  some  scraps  of  the 
same  metal; 

A  case  knife; 

Quicksilver,  salt  and  bluestone; 

A  strip  of  wood  for  stirring,  and  patience. 

Persons  who  are  accustomed  to  such  operations 
can  make  this  test  on  1000  grains  of  ore,  and,  to 
such,  the  following  statement  may  be  more  accept- 
able than  the  foregoing  details:  A  weighed  quan- 
tity of  the  pulverized  ore  is  digested  in  a  glass  or 
porcelain  vessel,  with  a  solution  sulphate  of  copper 
and  salt,  metallic  copper,  and  quicksilver,  and  the 
resulting  amalgam  is  estimated  proportionally  for 
a  ton  of  ore.  If  a  fire  assay  is  made  of  the  un- 
worked  residue  of  the  sample,  a  comparison  of  the 
two  results  will  indicate  the  working  percentage. 

[14.]  Almost  any  ore  will  yield  a  portion  of  its 
silver  to  this  treatment,  and  all  those  which  give  a 
good  result,  can  be  worked  in  the  large  way  by 
Aaron's  process;  some  by  Patch  en's  process,  and  a 
few  by  simple  pan  treatment.  Ores  which  will  not 
yield  to  it  cannot  be  treated  successfully  by  any  of 


22  TESTING   AND   WORKING. 

these  methods,  but  will  in  general  be  best  worked 
by  roasting,  and  I  know  of  none  in  this  country 
which  cannot  be  so  worked  successfully. 

The  test  by  roasting  cannot  be  made  reliably  on 
a  very  small  scale;  but  this  is  not  necessary,  as  it 
may  be  taken  for  granted ,  that,  setting  aside  smelt- 
ing ores,  roasting  will  give  a  fair  result  if  rightly 
managed. 


WORKING  ORES. 


[15]  Aaron's  process  is  essentially  similar  to  the 
working  test  just  described.  I  have  called  it  Aaron's 
process  because  I  invented  ic,  independently,  in 
1867,  being  led  to  it  by  considering  the  reactions 
of  the  Patio,  and  because  I  have  reduced  it  to  a 
fair  degree  of  practicability.  My  first  operation 
was  conducted  on  about  a  grain  of  ore  in  a  minute 
porcelain  cup,  with  the  aid  of  a  copper  belt-rivet; 
the  next  was  on  five  pounds  of  ore  in  a  kettle;  then 
on  a  ton  in  a  wooden  barrel,  and  subsequently, 
thousands  of  tons  have  been  worked  by  it,  and 
near  a  million  dollars  extracted.  I  soon  found 
that  the  process  was  similar  to  the  Mexican  fon- 
don,  which,  however,  never  advanced  beyond  a  very 
rude  and  primitive  stage  in  the  hands  of  the  Mex- 
icans, and  was  in  that  form  totally  unadapted  to 
our  day  and  country.  The  loss  of  quicksilver  was 
enormous,  except  when  the  ores  consisted  of  chlo- 
rides, bromides,  and  iodides,  which  do  not  require 


Z4  TESTING   AND   WORKING 

the  use  of  bluestone  or  magistral,  being  readily 
worked  in  copper  or  iron  pans,  with  salt  and  quick- 
silver alone.  My  process,  as  now  worked,  involves 
no  greater  loss  of  quicksilver  than  other  methods 
of  amalgamation  in  barrels  or  pans,  but  rather 
less,  and  the  chemical  and  mechanical  treatment 
differ  materially  from  the  old  fondon. 

[16.]  The  ore,  crushed  wet  or  dry,  and  at  least 
fine  enough  to  pass  through  a  40-mesh  wire  cloth, 
is  put  into  Aaron's  amalgamator,  or  a  wooden  amal- 
gamating barrel, together  with  a  quantity  of  met- 
allic copper,  50  or  100  pounds  of  salt,  and  enough 
water  to  form  a  pulp  of  medium  consistency.  -  A 
certain  quantity  of  dichloride  of  copper  is  added, 
the  barrel  closed  and  put  in  motion,  and  its  con- 
tents heated  by  means  of  steam  admitted  through 
the  journal.  When  the  pulp  is  boiling  hot,  a  little 
of  it  is  taken  in  a  small  porcelain-lined  sheet 
iron  saucepan,  and  tested  for  copper  in  solution, 
with  the  blade  of  a  case  knife,  as  already  described. 
If  no  copper  is  found,  more  dichloride  is  put  in, 
and  the  test  repeated  after  the  barrel  has  been 
again  in  motion  some  little  time. 

[17.  ]    When  the  presence  of  a  solution  of  copper 


SILVER  ORES.  25 

is  indicated  by  a  deposit  on  the  knife  blade,  ^re- 
membering the  remark  about  a  black  stain),  quick- 
silver is  put  in,  and  the  barrel  is  kept  in  mo- 
tion from  6  to  12  hours,  during  which  it  will 
not  usually  require  more  steaming,  and  being  again 
stopped,  a  little  pulp  is  taken  as  before,  diluted 
with  some  hot  water,  adding  a  little  salt  to  main- 
tain the  strength  of  the  brine,  and  is  tested,  while 
kept  boiling  hot  with  a  few  live  coals,  for  silver, 
with  a  strip  of  sheet  copper,  just  as  directed  for 
making  the  working  test.  When  no  silver  can  be 
found,  the  barrel  is  discharged  into  the  separator 
and  recharged  as  before. 

[18.]  In  treating  ores  raw,  when  crushed  wet, 
some  inconvenience  results  from  the  condensation 
of  the  steam  used  for  heating,  by  which  the  pulp  is 
too  much  diluted.  This  may  be  remedied  by  using 
superheated  steam,  whereby  not  only  is  the  dilu- 
tion avoided,  but  the  pulp  may  even  be  thickened 
if  necessary.  If  the  ore  is  crushed  dry,  a  small 
portion  of  the  charge  is  kept  back,  till  the  contents 
of  the  barrel,  or  other  machine,  are  heated,  when  a 
quantity  sufficient  to  make  the  pulp  of  the  desired 
consistency  is  put  in. 
2 


26  TESTING   AND   WORKING 

[19.]  The  dichloride  of  copper  is  prepared  as 
follows:  22  pounds,  of  bluestone  and  10  pounds  of 
salt,  dissolved  in  water,  are  boiled,  together  with 
five  pounds  of  iron  borings,  in  a  steam  heated  ro- 
tating barrel,  or  a  vat,  till  the  iron,  and  copper  pre- 
cipitated by  it,  have  quite,  or  almost  wholly  disap- 
peared, being  replaced  by  a  light  colored  powder, 
which  is  dichloride  of  copper.  Or,  11  pounds  of 
bluestone  and  5  pounds  of  salt  are  boiled,  together 
with  a 'quantity  of  scrap  copper,  till  the  solution  is 
no  longer  green,  when  the  same  quantity  of  dichlo- 
ride of  copper  is  formed.  If  the  salt  is  impure,  a 
larger  proportion  must  be  employed;  an  excess 
does  no  harm,  but  in  no  case  should  the  liquor  be 
thrown  away,  as  it  may  contain  some  dissolved  cop- 
per, so  that  it,  as  well  as  the  precipitate,  should  be 
used.  The  dichloride  of  copper  should  not  be 
much  exposed  to  the  air,  as  it  thereby  becomes 
changed. 

[20.]  Protochloride  of  copper,  most  convenient- 
ly prepared  by  dissolving  some  bluestone,  with  half 
its  weight  of  salt,  in  water,  may  be  used  in  place 
of  dichloride,  and  in  precisely  the  same  manner  as 
to  tests,  etc. ,  but,  as  it  attacks  quicksilver,  the  fol- 


S1LVEE   ORES.  27 

lowing  precautions  are  necessary :  The  quicksil- 
ver must  not  be  put  in  till  some  hours  after  the 
pulp  has  been  heated  and  worked  with  the  copper 
balls,  so  that  the  chloride  of  copper  has  lost  its 
power  of  acting  on  it,  and  then,  in  order  that  there 
may  be  no  quicksilver  in  the  amalgamator,  or  stick- 
ing to  the  copper  when  the  new  charge  of  ore  is 
put  in,  it  must  be  used  very  sparingly,  not  more 
than  twice  the  weight  of  the  silver  in  the  ore  being 
used,  or  about  3  pounds  to  $100.  The  amalgam 
is  then  found  mixed  through  1he  pulp  in  the  form 
of  a  coarse,  gray  powder,  or  little  flakes,  and  must 
be  collected  by  working  the  pulp  in  a  wooden  pan, 
with  an  additional  quantity  of  quicksilver,  and 
slightly  diluted  with  water,  so  that  it  may  be 
drawn  off,  leaving  the  bulk  of  the  fine  amalgam  in 
the  pan,  to  the  separator,  where  it  is  treated  for 
recovery  of  copper  and  quicksilver,  as  described 
hereafter. 

[21.]X()res  containing  carbonate  of  copper  do 
not  require  the  dichloride  prepared  as  above.  In- 
stead of  it  sulphate  of  iron  is  used,  and  is  put  at 
once  into  the  barrel  with  the  ore  and  salt;  it  pro- 
duces the  dichloride  and  protochloride  of  copper 


28  TESTING  AND   WORKING 

from  the  carbonate  in  the  ore.  \Sulphurousacid  is 
better  than  sulphate  of  iron  for  this  purpose,  as 
it  forms  only  the  dichloride  of  copper,  besides 
having  other  advantages,  and  being  much  cheaper, 
for  as  it  is  only  the  sulphuric  acid  in  the  sulphate 
of  iron  which  is  useful,  one  pound  of  sulphur  in 
the  form  of  sulphurous  acid,  is  equal  to  about  10 
pounds  of  sulphate  of  iron.'/  The  sulphurous  acid 
is  made  by  burning  sulphur,  and  the  vapors  are 
either  forced  into  the  wet  ore-pulp,  or  condensed 
in  water,  with  which  the  dry  ore  powder  is  after- 
wards mixed.  I  have  a  patent  on  this  reagent  for 
the  purpose  of  amalgamation. 

[22.]  I  have  often  been  asked,  when  working 
this  class  of  ores,  why  I  used  the  copper  balls  in 
the  barrel  when  there  was  so  much  copper  in  the 
ore.  The  reason  is  that  the  process  requires  cop- 
per in  solution,  and  metallic  copper.  Now  the 
copper  in  the  ore  is  not  metallic;  it  is  not  really 
copper,  it  is  carbonate  of  copper,  just  as  iron  rust, 
though  formed  from  iron,  will  not  do  to  make  a 
crowbar  of,  so  in  our  operation  the  balls  of  copper 
must  be  retained.  Still  the  copper  contained  in 
such  ores,  can  be  and  is  utilized  as  follows :  a  cer- 


SILVER    OEES.  29 

tain  quantity  of  iron  borings  is  put  into  the  barrel, 
together  with  the  charge  of  ore,  salt  and  sulphate 
of  iron,  and  by  a  complex  reaction,  which  I  shall 
not  explain  here,  economizes  the  consumption  of 
the  balls  by  producing  copper  from  the  ore,  with- 
out, however,  diminishing  the  quantity  in  solution. 
The  quantity  of  iron  to  be  used  in  this  way  depends 
on  several  circumstances,  and  varies  from  2  pounds 
to  50  pounds  to  the  ton  of  ore.  Rich  ore  will  bear 
more  than  that  which  is  poor,  but  it  must  be  regu- 
lated by  the  quality  of  the  bullion,  as  too  much 
produces  a  coppery  amalgam.  It  is  not  essential 
to  use  it  at  all,  but  it  is  economical.  Iron  is  not 
used  in  this  process  except  when  working  ores  con- 
taining carbonate  of  copper,  or  as  already  shown, 
in  preparing  the  dichloride,  and  as  the  quantity 
must  in  all  cases  be  under  control,  the  process 
cannot  be  worked  in  iron  pans. 

[23.]  The  quantity  of  chemicals,  iron,  etc.,  re_ 
quired  in  working  any  given  class  of  ore  is  soon 
found,  so  that  after  working  a  couple  of  charges 
there  is  no  need  of  testing  every  time.  In  Benton 
the  average  quantity  of  sulphate  of  iron  used  was 
22  pounds  per  ton  of  ore. 


30  TESTING  AND   WORKING 

[24.]  Carbonate  of  lime  and  of  lead,  if  in  great 
quantity,  make  these  processes  expensive  by  con- 
suming too  much  of  the  chemicals,  and  can  only 
be  overcome  cheaply,  by  means  of  sulphurous  acid, 
which,  moreover,  has  many  advantages  over  sul- 
phate of  iron  in  working  coppery  ores. 

[25.]  Aaron's  process  has  the  great  advantage 
of  always  giving  fine  bullion,  no  matter  how  base 
may  be  the  ore,  if  properly  managed,  and  the 
quicksilver  always  comes  out  clean.  Among  the 

ores  which  can  be  worked  by  it  are  .partzite,  stete- 

*  *   A!^K~ 
feldtite,    silver  glance,   carbonate  of  silver,  ruby 

silver,  etc. ;  galena,  zincblende  and  copper  pyrites, 
containing  silver,  do  not  yield  well. 

[26.]  The  ores  of  this  country  are  usually  very 
mixed,  and  often  it  is  difficult  to  determine  in 
what  condition  or  combination  the  silver  exists  in 
them,  so  it  is  not  always  safe  to  say  what  process 
will  prove  best,  without  making  a  trial.  Some 
ores  which  prove  refractory  in  the  raw  state,  may 
be  made  workable  by  roasting  in  open  or  covered 
heaps  or  kilns.  It  is  easily  tried  by  burning  a 
small  pile  and  then  taking  a  fair  sample  and  mak- 


SILVER   ORES.  /  «* .  J>          8x4^4 

ing  a  test  on  5  pounds.      Chloride  ores^yajreadjr/  ^ 
stated,  require  no  special  treatment,  being  f  eC&ty       ' ' 
worked  in  barrels  or  pans  with  salt  and  quicksilver; \y 
but  I  wish  to  observe  that  of  the  ores  commonly     <^ 
called  "chlorides"  by  the  miners,  not  one  in  a  hun- 
dred contains  any  chloride,  being,  in  nearly  every 
case,  simply  an  ochreous  compound  of  base  metal, 
which  may  or  may  not  carry  some  silver. 

[27.]  A  separator  with  an  iron  bottom  which  is 
scoured  by  wooden  muller  shoes,  is  used  in  con- 
nection with  this  process,  by  which  means  a  large 
loss  of  quicksilver  is  avoided.  The  machine  I  have 
found  to  answer  best  is  described  further  on.  In 
it  the  warm  pulp  as  it  comes  from  the  barrel,  con- 
taining dissolved  copper,  is  worked,  without 
addition  of  water,  for  a  greater  or  less  length  of 
time,  whereby  a  quantity  of  copper  amalgam  is 
formed  on  the  iron  bottom,  and  nearly  all  the 
mercury  is  saved.  On  this  account  the  bulk  of 
quicksilver  and  amalgam  is  not  allowed  to  pass  to 
the  separator,  where  it  would  be  mixed  with  the 
base  amalgam  there  formed,  but  is  retained  in  the 
trough  through  which  the  pulp  flows,  by  means  of 
a  riffle,  or  "pot,"  and  after  being  sponged  clean, 
is  led  by  an  iron  pipe  to  the  strainer, 


32  TESTING   AND   WORKING 

The  base  amalgam  from  the  separator  may  be 
disposed  of  in  several  ways — 

1st.  It  is  returned  to  the  barrel,  where  it 
answers  the  same  purpose  as  metallic  copper,  and 
saves  the  consumption  of  the  balls,  but  too  much 
will  spoil  the  bullion. 

2d.  It  is  retorted,  and  as  in  this  operation 
there  occurs  a  partial  separation  of  the  copper 
from  the  silver,  of  which  latter  there  is  always 
more  or  less  present,  the  spongy  metal  is  broken 
to  pieces,  and  assorted  into  two  or  three  grades; 
the  finer  part  is  melted  and  sold,  and  the  nearly 
pure  copper  is  used  to  make  the  dichloride  for  fu- 
ture use. 

3d.  The  retorted  metal  is  melted,  and  cast  into 
bars  or  balls  for  use  in  the  barrel. 

Thus  the  metallic  copper  consumed  in  the  amal- 
gamator, and  with  some  ores  that  also  which  is 
used  as  dichloride  or  bluestone,  is  recovered  at 
the  expense  of  the  iron  bottom  of  the  separator, 
and  in  the  case  of  ores  containing  carbonate  of 
copper,  as  much  copper  as  is  desired  may  be  made 
so  long  as  there  is  any  left  in  the  ore  to  get  out. 
It  would  be  perfectly  possible  to  work  copper  ore 
for  copper  on  this  plan,  but  we  can  do  better  by 
leaching  on  the  Hunt  and  Douglass  plan. 


SILVER    ORES.  33 

In  working  the  ores  of  Mono  County,  it  was 
found  that  when  a  separator  made  entirely  of  wood 
was  used,  a  large  quantity  of  quicksilver  passed  off 
in  the  form  of  a  red  powder,  easily  detected  by 
panning,  but  containing  no  visible  metallic  quick- 
silver; the  use  of  the  iron  bottom  prevented  this 
loss  by  decomposing  the  red  powder,  but  in  order 
to  produce  this  effect  there  roust  be  copper  in  solu- 
tion in  the  pulp,  which  however  is  always  the  case 
if  it  has  been  properly  worked  in  the  barrel.  After 
a  sufficient  time  the  separator  is  filled  with  water, 
and  subsequently  discharged  in  the  usual  way  by 
plug-holes.  Amalgamators  specially  adapted  to 
this  process,  will  be  described  in  their  place. 

PATCHEN'S  PROCESS. 

[28.]  The  Patio  is  the  mother  of  Aaron's  pro- 
cess, the  Fondon  is  its  elder  sister,  and  Patchen's 
process  is  a  younger  member  of  the  same  family. 
As  it  is  patented,  a  minute  description  is  not  needed 
here.  It  consists  essentially  in  treating  the  pulver- 
ized ore  with  dichloride  of  copper,  and  without 
quicksilver,  in  a  copper-lined,  steam-heated  vessel, 
after  which  it  is  transferred  to  an  iron  pan,  and 
worked  with  quicksilver.  The  process  commends 
2* 


34  TESTING   AND   WORKING 

itself  to  Virginians  by  making  use  of  tke  iron  pans 
with  which  all  their  mills  are  provided,  but  equally 
good  results  are  got  by  Aaron's  process,  and  as 
the  tests  described  for  them  are  not  applicable  to 
this,  the  operation  is  not  so  easily  regulated,  whilst 
in  some  cases  the  bullion  obtained  is  not  fine, 
owing  to  the  action  of  the  iron  pan  in  extracting 
copper  or  lead. 

ROASTED  ORES. 

[29.]  Koasted  ores  may  be  worked  in  ban-els 
with  scrap  iron  or  copper  balls,  or  in  iron  pans. 
Ores  containing  much  copper,  lead,  etc.,  will  not 
yield  fine  bullion  in  pans,  unless  the  roasted  ore  is 
first  washed  in  filter  vats  with  acidulated  water,  to 
dissolve  out  the  salt  which  may  remain  after  roast- 
ing, and  the  base  metal  chlorides,  some  of  which 
are  not  soluble  in  plain  water.  Barrels  with  scrap 
iron  give  a  finer  bullion  from  such  ores,  than  pans, 
but  any  roasted  ore  will  yield  fine  bullion  if  worked 
in  barrels  with  copper  balls,  or  in  the  new  machine 
hereafter  described.  When  these  machines  or  bar- 
rels are  used,  it  is  sometimes  necessary  to  sift  the 
ore  to  remove  lumps  formed  in  the  furnace,  which 
are  either  returned  to  the  battery  or  ground  in  a 


SILVER    0 

pan.  On  this  account,  pans  are  usi 
though  the  wisdom  of  the  choice  is 
especially  if  the  ore  is  base.  I  have  in  some 
got  90  per  cent,  of  the  silver  from  roasted  ore,  in 
barrels,  without  sifting.  As  nearly  all  the  salt  used 
in  roasting  is  decomposed  or  evaporated,  it  is  very 
advantageous  to  add  a  little  to  the  pulp  in  the 
amalgamator;  it  acts  by  dissolving  the  chloride  of 
silver,  which  aids  its  reduction  to  metal.  .  The 
quality  of  bullion  obtained  from  base  roasted  ore, 
when  worked  in  iron  pans,  may  be  improved  by 
adding  a  certain  quantity  of  lime  or  ashes,  but  an 
excess  must  be  avoided. 

[30.]  It  is  a  common  error  to  suppose  that  the 
object  of  roasting  is  to  "  destroy"  the  base  metals, 
and  this  absurdity  has  been  encouraged  by  some 
who  ought  to  know  better;  hence  many  think  that 
roasted  ore  ought  always  to  yield  fine  bullion. 
The  truth  is,  that  silver  ore  is  roasted  with  salt  for 
the  purpose  of  changing  the  various  and  refractory 
compounds  of  silver  into  one  known  and  easily 
reduced  compound,  namely,  chloride.  Now  if 
this  could  be  done  without  affecting  the  base 
metals  at  all,  we  should  always  get  fine  bullion, 


36  TESTING  AND    WORKING 

because  the  base  metals  would  not  be  extracted  by 
the  pan;  but  it  unfortunately  happens  that  the 
roasting',  which  aids  us  to  get  the  silver,  puts  the 
copper,  lead,  etc.  into  a  similar  condition,  and 
they  are  not  driven  off  to  any  great  extent  in  the 
operation.  It  is  true  that,  by  a  certain  modifica- 
tion of  the  roasting  process,  the  base  metals  can 
again,  in  a  measure,  be  changed  so  as  not  to  be 
amalgamated,  but  this  causes  loss  and  expense,  and 
is  never  fully  effective,  besides  which  the  chemical 
action  in  the  pan  is  such  as  first  to  reproduce  and 
then  decompose  the  base  metal  chlorides,  so  that 
after  all  they  find  their  way  into  the  amalgam  more 
or  less;  nor  can  this  action  be  entirely  prevented 
by  the  use  of  potash  or  lime  in  the  pan,  since  the 
quantity  of  these  which  would  produce  the  re- 
quired effect,  would  also  interfere  with  the  amal- 
gamation of  silver. 

[31.1  The  chloridizing  roasting  of  silver  ore  is 
not  so  mysterious  or  difficult  an  operation  as  some 
suppose,  and  others  pretend — that  is,  practically. 
The  proof  of  this  is  the  success  attained  by  many 
persons  of  no  scientific  attainments,  and  of  quite 
moderate  ability.  What  is  principally  necessary, 
is  courage  to  try,  and  then  courage  to  try  again. 


SILVER   ORES.  37 

Of  course  in  a  custom  mill,  where  different  kinds 
of  ore  are  constantly  coming  in,  and  where  no  fail- 
ures are  allowable,  knowledge  and  experience  are 
indispensable  in  the  operator;  but  any  person  of 
common  intelligence  may  soon  learn  to  roast  a 
given  kind  of  ore,  especially  when  he  is  his  own 
boss,  with  no  one  to  grumble  at  his  mistakes.  In 
large  operations  the  mechanical  roasters,  such  as 
Stetefeldt's,  White's  or  Bruckner's,  should  be  used; 
but  for  a  small  mill,  working  about  two  tons  of  ore 
per  day,  and  owned  by  the  miner  himself,  a  rever- 
beratory,  such  as  I  shall  describe,  will  answer  per- 
fectly, though  if  one  can  afford  to,  get  a  Bruckner 
and  run  it,  say  one  or  two  days  in  a  week,  the 
work  will  be  done  cheaper. 

[32.]  To  roast  ores  well  requires  practice,  the 
directions  I  shall  give,  will  therefore  be  brief  and 
general  in  their  character,  to  be  interpreted  and 
applied  with  judgment.  A  knowledge  of  the 
theory  should  be  indispensable  to  the  professional 
man,  who  ought  to  know  the  why,  as  well  as  the 
how,  to  do  things;  but  our  "honest  miner"  only 
wants  to  know  how  to  get  a  fair  percentage  of  the 
silver  out  of  his  particular  ore, 


38  TESTING   AND   WORKING 

[33.]  The  essentials  of  chloridizing  roasting  are 
heat,  air,  sulphur  and  salt.  Heat  is  obtained  by 
means  of  fire;  air  enters  the  furnace  through  the 
fire-place,  and  through  openings  in  the  sides;  salt 
is  supplied  by  the  operator,  and  sulphur  either 
exists  naturally  in  the  ore,  or  is  added  to  it  in  some 
shape.  Ores  having  lime  in  them,  require  more 
sulphur  than  such  as  have  a  quartz  gangue. 

[34.]  Night  is  the  best  time  to  study  roasting, 
as  the  different  degrees  of  heat  are  then  most 
readily  seen,  and  for  the  same  reason  the  furnace 
is  best  in  a  place  where  there  is  not  too  much  light 
in  daytime.  What  I  say  about  the  heat  must  be 
considered  as  referring  to  appearances  as  seen  at 
night,  and  when  the  fire  is  not  flaming. 

[35.]  The  furnace  is  heated  to  a  dark  red,  the 
ore  is  put  in,  spread  on  the  hearth,  and  stirred  at 
short  intervals  with  hoe  or  rake.  From  5  to  10 
per  cent,  of  salt  is  charged  with  the  ore.  It  is  best 
to  begin  with  the  larger  quantity,  and  when  the 
roasting  is  found  to  yield  a  good  result,  less  salt 
may  be  tried,  till  the  lowest  quantity  that  will 
answer  is  found.  If,  on  stirring  the  ore,  the  sul- 


SILVER   ORES.  39 

phur  is  seen  to  burn  with  a  blue  flame,  the  fire  is 
kept  very  low,  and  the  ore  stirred  continually  till 
no  more  sulphur  is  seen  to  burn,  which  may,  in 
extreme  cases,  take  several  hours,  during  which 
the  fire  is  allowed  to  almost  go  out.  The  heat  is 
then  raised  slowly  to  about  a  cherry  red,  the  ore 
still  being  stirred,  and  not  till  a  sample,  taken 
from  the  furnace  with  a  drill  spoon,  smells  no  longer 
of  burning  sulphur,  is  the  heat  raised,  gradually, 
to  a  light  red,  approaching  to  white,  but  not  so  as 
to  slag  the  ore,  which  at  this  time  assumes  a  con- 
dition which  has  been  described  as  woolly,  spongy 
or  feathery,  and  swells  greatly,  while,  whereas  at 
an  earlier  stage  it  appeared  very  mobile,  running 
and  spreading  like  water,  it  is  now  rather  sticky, 
and  "stays  put."  As  at  this  time  less  constant 
stirring  is  needed,  this  is  a  good  opportunity  to 
scrape  the  ore  thoroughly  out  of  all  the  corners, 
piling  it  in  the  middle  of  the  hearth,  after  which  it 
is  again  spread.  When  all  the  ore  is  equally  heated, 
so  that  on  stirring  clear  to  the  bottom,  and  in  the 
corners,  no  black  places  are  seen,  the  fire  is  allowed 
to  go  down,  ready  for  another  charge,  the  ore 
being  drawn  away  from  the  bridge,  and  moved 
only  enough  to  prevent  any  part  from  getting  so 


40  TESTING   AND   WORKING. 

hot  as  to  melt.  It  is  well  to  draw  it  into  a  heap 
ready  for  discharging,  which  is  done  as  the  fur- 
nace cools  off. 

[36.]  On  taking  a  sample  of  the  roasted  ore, 
and  panning  it  down  in  a  saucer,  no  raw  sulphurets 
should  be  seen.  Lumps,  more  or  less,  there  will 
be,  but  there  should  be  no  slagged  or  sintured 
ones,  except  as  occasionally,  by  accident,  a  little 
ore  has  stuck  to  the  bricks,  and  after  being  slightly 
melted,  has  been  scraped  off  again;  and  right  here 
I  want  to  say  something  about  stirring.  Never 
push  the  hoe  so  as  to  jam  the  ore  against  the  side 
of  the  furnace,  but  when  it  is  within  about  a  foot 
of  the  bricks,  lift  it  clear  of  the  ore  by  lowering 
the  handle,  push  it  on  over  the  ore,  and  then  let  it 
down  and  move  it  the  other  way.  Thus  you  will 
avoid  plastering  the  sticky  ore  on  to  the  bricks, 
and  sare  much  trouble. 

[37.]  The  chief  danger  in  roasting  is  in  apply- 
ing too  high  a  heat  at  first,  but  ores  which  contain 
little  sulphur  may  be  heated  more  rapidly  than 
those  which  have  much.  Some  ores  with  calca- 
reous gangue  roast  to  90  per  cent,  without  at  any 


SILVER   ORES.  41 

time  smelling  strongly  of  sulphur  or  of  chlorides. 
The  color  of  the  roasted  ore  varies  greatly,  depend- 
ing on  the  constituents,  the  degree  of  heat  to 
which  it  is  exposed,  and  the  exposure  to  air,  both 
in  the  furnace  and  after  it  is  withdrawn.  The 
knowing  just  when  to  discharge  the  ore  is  a  mat- 
ter of  judgment  and  experience,  the  only  reliable 
test  of  its  being  well  roasted,  except  by  working- 
it,  being  such  as  to  require  a  knowledge  of  assay- 
ing. There  is  however,  a  test,  in  addition  to  that 
by  washing  in  a  saucer  already  spoken  of,  which 
may  afford  a  clue.  It  consists  in  throwing  a  little 
of  the  red  hot  ore  into  a  dish  of  water;  well  roasted 
ore  will  diffuse  a  white  cloud  in  the  water,  whilst 
if  the  roasting  is  not  finished,  the  cloud  will  be 
more  or  less  yellow. 

[38.]  Ore  which  fails  to  roast  well  for  want  of 
sulphur,  requires  the  addition  of  2  or  3  per  cent, 
of  iron  pyrites,  or  sulphate  of  iron,  or  a  little  pul- 
verized sulphur. 

LEACHING  PROCESSES. 

[39.]  Leaching  processes  are  of  several  kinds, 
for  gold,  silver,  or  copper,  or  all  three  combined. 


42     *  TESTING   AND   WORKING 

They  all  involve  the  necessity  of  roasting,  with  or 
without  salt.  The  roasted  ore  is  put  into  filtering 
vats,  and  the  metals  are  extracted,  just  as  lye  is 
extracted  from  ashes,  by  passing  through  the  mass 
a  fluid  which  dissolves  them,  after  which  they  are 
separated  from  the  fluid  by  the  addition  of  a  sub- 
stance which  throws  them  down,  either  in  a  metal- 
lic state,  or  as  insoluble  compounds,  which  must  be 
again  treated  for  the  pure  metal.  These  processes 
are  very  admirable,  and  in  many  cases  cheaper 
than  amalgamation.  Some  difficulty  is  frequently 
found  in  getting  the  dissolving  fluid  through  the 
ore  fast  enough,  and  to  overcome  this,  I  have  con- 
trived two  different  machines,  to  be  described 
hereafter. 

SMELTING. 

[40.]  It  has  already  been  mentioned  that,  in 
certain  circumstances,  smelting  is  the  best  process 
for  extraction  of  silver.  As  I  have  no  experience 
in  this  line,  any  instructions  I  could  give  would 
only  be  copied  from  some  one  else,  to  which  some 
one  else  I  therefore  beg  to  refer  the  reader  who  is 
anxious  to  smelt  his  ore.  He  can  find  much  about 
it  in  various  books,  after  studying  which  he  will 
still  have  much  to  learn. 


/%>    *& 

SILVER    ORES.  /    K  4O       < 

/^\  V^;'  > 


[41.]     When  a  Mexican  finds 
get  galena  in  the  vicinity,  he  puts  up  a  litfl^tfur-          ^ 
nace  of  adobes,  smelts  out  his  silver-lead,  refinery 
in  another  little  furnace,  and  buys  his  beans  wit3j    "M.      , 
the  proceeds.     Why  cannot  intelligent  Americans, 
who  have  opportunities  of  seeing  smelting  carried 
on,  go  and  do  likewise  ?     In  course  of  time  the 
knowledge  would  spread,  and  many  honest  miners 
might  profit  by  their  discoveries,  instead  of  wait- 
ing for  capital,  or  abandoning  their  mines,  because 
they  cannot  sell  them. 

A  MEXICAN  PROCESS. 

[42.  ]  The  terreros,  containing  fragments  of  ores, 
consisting  of  oxides  and  sulphides,  are  ground  to 
an  impalpable  powder  in  the  arrastra,  with  addition 
of  the  new  magistral,  for  some  hours,  at  the  ex- 
piration of  which  period  quicksilver  is  added,  and 
the  grinding  continued  till  all  the  silver  be  amal- 
gamated. Ores  containing  chloride,  or  iodide  of 
silver  do  not  yield'to  this  process,  and  compounds  of 
chlorine  in  every  form  must  be  carefully  excluded. 
The  grinding  must  be  done  in  stone,  not  in  iron 
arrastras.  Excess  of  the  magistral  is  to  be  avoided, 
as  it  vitiates  the  amalgam. 


44  TESTING   AND   WOBKING 

The  new  magistral  is  made  by  digesting  sub- 
oxide  of  copper  with  sulphuric  acid,  in  equivalent 
proportions,  which  forms  an  intimate  mixture  of 
sulphate  of  copper  and  finely  divided  metallic 
copper. 

For  the  above  description  I  am  indebted  to  Mr. 
John  Scott,  of  San  Francisco,  Assay  er.  I  know 
nothing  more  about  the  process,  but  it  is  not  clear 
to  me  that  a  mixture  of  cement,  copper  and  blue- 
stone  would  not  answer  as  well  as  the  above  prep- 
aration, which  must  be  rather  expensive. 

KRCENCKE'S  PROCESS. 

See    ^B 


[43.]  Kroencke's  process  is  practiced  in  Copiapo, 
Chili,  and  is  described  as  follows  in  the  American 
Chemist: 

"  The  ores  of  this  district,  consisting  of  the 
chloride,  iodide  and  bromide  of  silver,  together 
with  various  sulphides  of  silver,  occur  in  Jura  lime- 
stone and  marl,  diabase  and  porphyry,  and  have 
associated  with  them,  as  veinstones,  calcite,  heavy 
spar,  gypsum,  amianthus,  kaolin,  and  in  the  upper 
levels,  ferruginous  clay.  There  has  never  been 
any  difficulty  in  completely  extracting  the  metal 
from  the  chloride,  bromide  and  iodide  by  amal- 


SILVEB   OEES.  45 

gamation,  while  the  sulphurets  have  alway's  been 
the  cause  of  large  losses  in  the  residues.  Krcencke 
first  based  his  process  on  the  treatment  of  these 
residues  and  subsequently  extended  it  so  as  to 
treat  the  pure  sulphides,  arsenides  and  antimo- 
nides  of  silver.  The  writer  made  a  series  of  experi- 
ments in  order  to  arrive  at  a  theory  of  the  process. 
He  found  : 

1st.  —  If  ruby  silver  be  digested  in  a  finely  pul- 
verized condition  with  a  hot  concentrated  solution 
of  cupric  sub-chloride  and  sodium  chloride,  a 
chemical  reaction  is  soon  perceptible,  the  powder 
turning  black.  An  analysis  of  this  powder  shows 
the  formation  of  argentic  sulphide  and  cupric  sub- 
sulphide,  while  antimonic  chloride  is  found  in  the 
solution.  The  reactions  are  — 

3AgS,SbS;,+3(Cu2Cl)+NaCl=3AgS  +  SbCl3+3(Cu2S)  + 
NaCl. 

2d.  —  If  the  silver  sulphide  thus  obtained  be 
again  treated  in  a  hot  solution  with  cupric  sub- 
chloride  and  sodium  chloride,  and  zinc  is  added, 
metallic  silver  is  almost  instantaneously  formed. 
The  reactions  are  — 


The  zinc  probably  acts  as  electro-positive  metal, 


46  TESTING   AND   WORKING 

predisposing  the  atoms  of  argentic  sulphide  and 
cupric  sub-chloride  to  a  mutual  exchange,  so  that 
the  cupric  sub-sulphide  and  argentic  chloride  are 
formed;  which  last  is  decomposed  in  a  nascent 
state  by  the  zinc,  with  the  formation  of  zinc  chlo- 
ride and  silver.  If  the  very  finely  divided  argentic 
sulphide  obtained  in  the  first  experiment  be  taken, 
the  action  of  the  reagents  is  almost  instantaneous. 
If,  however,  the  experiment  be  made  with  a  small 
piece  of  argentite  (AgS)  in  contact  with  a  small 
piec  3  of  zinc,  a  dull  white  coating  is  formed  on  the 
surface  of  the  argentite,  which  is  probably  argentic 
chloride,  and  which  only  assumes  a  metallic  ap- 
pearance with  prolonged  action  of  the  zinc. 

3d. — If  in  the  second  experiment  mercury  be 
also  added,  the  reduction  of  .the  silver  takes  place 
still  more  rapidly,  while  at  the  same  time  amalgam 
is  formed.  Lead  can  be  used  instead  of  zinc  and 
both  act  more  powerfully  when  used  in  the  form  of 
amalgam.  The  chief  points  in  this  method  of 
treatment  are :  .. 

1st. — The  use  of  a  hot  concentrated  solution  of 
cupric  sub- chloride  and  sodium  chloride,  especially 
of  the  latter,  in  order  to  retain  a  larger  amount  of 
cupric  sub-chloride  in  solution,  and  to  prevent  the 
formation  of  basic  copper  salts. 


SILVER  ORES.  47 

2d. — The  use  of  perfectly  dry  ore,  finely  pulver- 
ized, in  order  that  it  may  easily  absorb  the  solu- 
tion. Wet  ores  cause  the  formation  of  basic  salts, 
and  hence  loss  of  effective  cupric  sub-chloride,  as 
well  as  imperfect  impregnation. 

3d. — The  use  of  cupric  sub-chloride  and  of  lead 
or  zinc  in  combination  with  mercury  as  amalgam, 
in  such  quantities  that  the  reactions  described  may 
take  place  through  all  the  ore  without  any  excess 
of  the  last-mentioned  metals.  Since  an  excess  of 
cupric  sub-chloride  is  generally  used,  this  last  will 
be  decomposed  by  the  lead  (or  zinc)  and  copper 
formed,  which  pass  into  the  amalgam  and  whose 
removal  is  always  troublesome  when  present  in 
large  quantities.  Krcencke  treats  very  cuperif  erous 
amalgam,  after  having  been  squeezed  and  ground 
in  a  centrifugal  apparatus,  with  a  hot  solution  of 
cupric  chloride  in  order  to  extract  the  copper. 
(OuCl+Ciu=Cu9Cl.) 

4th. — It  is  always  advisable,  so  far  as  practicable, 
to  treat  ore  of  constant  composition,  as  otherwise 
experiments  on  a  small  scale  must  be  constantly 
made,  even  when  but  slight  variations  occur  in  the 
nature  of  the  ore.  The  presence  of  mere  traces  of 
blende  make  the  process  much  more  expensive, 


48  TESTING  AND   WOKKING- 

while  large  amounts  of  the  same  render  the  use  of 
this  method  impossible,  as  the  cupric  sub-chloride 
solution  is  instantly  decomposed  by  the  blende." 

THE  CHILIAN  PROCESS. 

[44.]  The  Chilian  process,  described  in  the 
Mining  and  Scientific  Press  of  January  10th,  1874,  is 
similar  to  Aaron's  process,  and  presents  no  advan- 
tages over  the  latter.  Other  methods  are  treated 
of  in  standard  works  on  the  subject. 


~ 

PULVERIZING  MACHINES°%/ 


[45.]  On  this  subject  I  shall  confine  my  re- 
marks to  machines  which  are  calculated  for  small 
operations.  The  splendid  stamp  batteries  no\\ 
used  in  our  first-class  mills  call  for  neither  descrip- 
tion nor  comment  here. 

THE  ARRASTRA. 

[46.]  The  arrastra  is  the  poor  man's  mill.  It 
consists  of  a  circular  pavement  of  stone,  upon 
which  the  ore  is  crushed  by  drawing  over  it  heavy 
stone  drags,  attached  by  chains  to  a  horizontal 
beam,  or  two  crossed  beams,  pivoted  to  a  post  in 
the  center  of  the  pavement,  motion  being  imparted 
either  by  water,  steam  or  horse-power.  The  stone 
pavement  is  surrounded  by  a  low  wall  of  rock  or 
wood,  to  retain  the  ore  and  water  during  the 
grinding,  and  in  which  is  a  gate  for  discharging 
the  pulp.  The  Mexicans  often  build  an  arrastra 
and  water  wheel  in  one,  the  beams  to  which  the 
drags  are  attached  being  prolonged  to  form  the 
3 


50  TESTING   AND   WORKING 

spokes  of  a  horizontal  reaction  wheel,  surrounding 
the  arrastra,  which  is  driven  by  a  stream  of  water 
from  an  inclined  sluice. 

[47. 1  When  used  for  grinding  silver  ore,  as  the 
quicksilver  is  not  put  into  the  arrastra,  there  is  no 
need  for  nicety  in  its  construction,  nor  for  tamping 
between  the  bottom  stones.  The  pavement  is 
made  of  rather  thin  stones  set  up  edgwise  on  a  bed 
of  sand,  and  should  not  be  laid  nearer  than  six 
inches  from  the  outer  wall,  or  the  center  post, 
otherwise  it  cannot  be  kept  flat  as  it  wears  down. 
The  spaces  thus  left  are  filled  with  gravel  or  clay. 
The  first  charge  worked  in  a  new  arrastra  consists 
of  some  barren  rock  and  clay,  by  which  all  inter- 
stices are  filled,  to  avoid  loss  of  valuable  ore.  An 
arraslra  of  10  feet  diameter,  with  drags  as  heavy  as 
can  be  drawn  by  a  2-horse  power  water  wheel,  or 
about  40  miners'  inches  of  water,  on  a  30  foot  over- 
shot wheel,  will  grind  from  1J  to  2  tons  of  ore  in  24 
hours,  in  charges  of  1,000  to  1,500  pounds.  It 
is  placed  so  that  the  pulp,  when  sufficiently  ground, 
flows  directly  from  it  to  the  amalgamator,  which  is 
on  a  lower  level.  The  pulp  is  kept  as  thick  as  is 
consistent  with  good  grinding. 


SILVER    ORES.  51 

[48.]  The  arrastra  may  be  made  to  grind  and 
discharge  continuously,  by  making  part  of  the  sur- 
rounding wall  to  consist  of  a  fine  screen  of  wire 
cloth,  through  which  the  pulp  flows  into  a  circular 
trough,  and  thence  to  a  vat.  Water  flows  in  con- 
tinuously, and  is  regulated  so  that  while  the  pulp 
is  thin  enough  to  flow  through  the  screen  when 
fine,  yet  the  sand  is  not  allowed  to  settle  so  as  to 
pack  on  the  bottom.  Ore  is  fed  in  at  inter- 
vals of  about  half  an  hour.  The  water  which  flows 
from  the  settling  vat  is  either  returned  to  the 
arrastra  by  means  of  a  wooden  pump,  or  an  archim- 
edian  screw,  or  it  is  led  into  a  reservoir  where  all 
suspended  matter  is  deposited.  From  8  to  10 
revolutions  per  minute  is  the  proper  speed  for  a 
10-foot  arrastra.  The  drags  are  as  heavy  as  the  power 
will  allow,  and  so  arranged  as  to  keep  the  bottom 
flat  as  it  wears;  they  are  attached  to  the  beams  by 
chains,  hooking  into  iron  eyebolts  set  into  the  rock 
with  melted  lead.  The  lead  after  being  poured  in, 
shrinks  in  cooling,  so  that  it  is  a  little  loose,  and 
it  is  tightened  by  being  driven  down  with  a  set  or 
punch.  The  drags  are  so  hung  that  the  forward 
end  is  lifted  a  little,  which  prevents  catching  and 
jerking;  they  are  also  retained  in  the  required 
position  by  stay  chains  at  the  rear  ends. 


52  TESTING   AND   WORKING 

[49.]  The  arrastra  will  grind  dry  as  well  as  wet, 
the  only  trouble  is  to  get  the  ore  ore  out  as  fast  as 
it  is  ground,  which  is  done  while  the  machine  is  in 
motion,  with  a  shovel,  and  it  is  sifted  by  a  rotating 
cylindrical  sieve,  so  arranged  that  the  coarse  stuff 
falls  again  into  the  arrastra.  This  is  very  poor 
work,  and  I  think  it  might  be  done  much  more 
conveniently  by  making  the  enclosing  wall  to  con- 
sist of  a  set  of  fine  screens  on  a  circular  framework; 
then,  by  means  of  a  sort  of  scoop,  somewhat  sim- 
ilar to  a  plowshare,  attached  to  one  of  the  rotating 
beams,  the  ore  will  be  thrown  forcibly  against  the 
screen,  and  the  fine  portion  will  pass  through. 
Such  an  arrastra  should  be  worked  at  15  to  20 
revolutions  per  minute,  should  have  a  light  remov- 
able cover,  and  the  bottom,  instead  of  being  flat, 
should  be  conical,  deepest  in  the  center,  where  the 
ore  should  be  fed  in  at  intervals.  By  this  arrange- 
ment very  coarse  ore  will  never  reach  the  screens 
to  break  them.  This  machine  should  be  driven  by 
a  belt,  to  avoid  serious  damage  in  case  of  a  drag 
getting  loose. 


SILVER    ORES.  53 


STAMP    BATTERIES. 

[50.]  Stamp  Batteries  with  4  light  stamps  of 
400  pounds  each,  are  preferable  to  those  with  two  of 
800  pounds  each,  because  the  parts  are  more  easily 
handled,  and  the  strain  on  the  machinery  is  more 
even.  In  wet  crushing  the  water  should  never,  in 
a  silver  mill,  be  allowed  to  run  off,  but  should  be 
pumped,  or  raised  with  a  screw,  from  the  settling 
tank,  and  passed  again  to  the  battery.  It  is  a 
good  plan  to  saturate  the  water  with  salt,  which 
facilitates  the  settling  of  slimes,  and  in  cold- 
weather,  tends  to  prevent  its  freezing.  Ore  can  be 
crushed  nearly  as  fast  dry  as  wet,  provided  it  can 
be  got  out  of  the  mortar  as  fast  as  it  is  reduced 
fine  enough.  The  discharge  is  facilitated  by  the 
following  arrangement: 

[51.]  In  place  of  the  usual  fine  screen  in  the 
mortar,  a  coarse  one  of  8  or  10  meshes  to  the  lin- 
ear inch  is  used;  the  ore  passing  rapidly  through, 
falls  on  to  an  inclined  apron,  formed  of  fine  wire 
cloth  stretched  on  a  frame,  which  is  hung  to  the 
battery  posts  by  hooks  and  eyebolts,  and  by  iron 


54  TESTING   AND    WORKING 

rods,  arranged  with  buckle  screws,  by  which  they 
can  be  lengthened  or  shortened  to  alter  the  inclin- 
ation as  required.  This  apron  is  five  or  six  feet 
wide  one  way,  and  as  wide  as  the  mortar  the  other 
way.  The  fine  ore  passes  through  into  a  receptacle 
below,  while  the  coarser  part  passes  over  the  apron 
and  falls  into  another  box.  In  some  cases  the 
coarse  matter  consists  almost  entirely  of  gangue, 
and  is  too  poor  to  be  worked,  so  that  a  certain 
concentration  of  the  richer  part  is  effected,,  but 
otherwise  it  is  returned  to  the  battery  together 
with  fresh  ore.  In  large  mills  conveyors  and 
elevators  dispose  of  the  coarse  and  fine  material 
respectively,  as  may  be  desired,  but  in  a  small  one 
this  is  done  by  hand.  No  "  joggler"  is  required  to 
shake  the  apron,  as  the  jarring  of  the  battery  to 
which  it  is  attached  is  sufficient.  In  order  to  be 
crushed  fast,  and  pass  readily  through  the  screens, 
ore  must  be  thoroughly  dried  by  artificial  heat,  es- 
pecially if  it  contains  clay  or  talc.  It  may  appear 
perfectly  dry  and  yet  contain  as  much  as  7  per 
cent,  of  water,  which  will  evaporate  in  the  heat 
produced  in  crushing,  and  by  condensing  on  the 
screens,  will  cause  the  fine  dust  to  stick.  The 
drying  may  be  done  in  a  kiln  or  oven,  and  the  ore 


SILVER    ORES. 


55 


fed  into  the  battery  quite  hot.  Where  the  ore 
has  to  be  burned  in  heaps  before  working,  it  will 
be  crushed  very  easily. 

CROCKER'S      TRIP-HAMMER 
BATTERY. 

[52.]  Crocker's  Trip-hammer  Battery  is  a  ma- 
chine of  which,  on  theoretical  grounds,  I  think 
very  favorably,  and  I  can  state  from  observation 
that  it  crushes  rock  very  fast.  The  advertisement 
states  that  it  crushes  600  pounds  per  hour,  requir- 
ing one-horse  power  to  drive  it.  The  advantage  of 
applying  a  given  amount  of  power  in  the  form 
of  a  light  hammer,  moving  at  high  velocity, 


rather  than  a  heavy  one  at  low  velocity,  is  well 
known,  and  is  illustrated  by  the  breaking  of  stone 
for  macadamized  roads  in  England,  which  is 


56  TESTING   AND   WORKING 

always  done  with  a  light  hammer  on  a  long  handle. 
In  this  battery  the  velocity  of  the  blow  is  obtained 
by  means  of  wooden  springs,  acting  under  the 
short  arms  of  the  levers  to  which  the  hammers  are 
attached.  As  to  the  stated  power  required,  it  is 
probably  under- estimated,  as  a  calculation  by  the 
usual  empirical  formula  of  mechanics,  based  on  the 
width  and  speed  of  belt  used,  gives  three-horse 
power  as  the  result.  These  calculations,  however, 
are  not  exact  unless  the  tension  and  material  of  the 
belt,  and  extent  of  contact  are  strictly  taken  into 
account;  and  I  find  that  a  calculation  based  on  the 
number  of  drops,  height  of  lift,  and  weight  of 
hammers,  gives  but  little  over  half  a  horse  power 
as  the  theoretical  amount  required ;  to  which  must 
be  added  an  unknown  quantity  for  friction,  and 
for  the  excess  of  weight  of  the  longer  ends  of  the 
arms  over  that  of  the  shorter  ends.  The  truth 
probably  lies  between  the  two  estimates.  Allow- 
ing, however,  that  it  takes  three-horse  power,  the 
performance  of  the  machine  shows  an  immense 
gain  over  that  of  the  common  battery,  while  its 
small  size  and  weight,  being  only  1,500  pounds; 
and  the  fact  that  it  requires  no  building  up,  being 
all  ready  for  use  when  bought,  and  may  be  taken 


SILVEK   OHES.  57 

to  pieces  and  set  up  by  one  man,  combined  with 
the  low  cost,  entitle  it  to  the  favorable  consider- 
ation of  miners,  and  adapt  it  especially  to  the  use 
of  that  class  of  small  mine  owners,  to  whom  prin- 
cipally I  address  myself. 

In  working,  the  springs  are  not  compressed  by 
the  direct  action  of  the  cams,  but  are  so  adjusted, 
that  if  the  cam  shaft  be  revolved  slowly,  no  com- 
pression takes  place;  but  at  the  high  speed  used 
in  actual  work,  the  acquired  momentum  of  the 
rising  hammers,  carries  the  levers  beyond  the 
direct  range  of  the  cams,  and  causes  the  short  ends 
to  come  in  contact  with  the  springs,  by  the  elas- 
ticity of  which  they  are  driven  upward,  causing 
the  hammer  to  descend  with  great  velocity.  The 
information  I  have  been  able  to  obtain  at  the 
foundry  does  not  indicate  any  undue  liability  to 
breakage. 

PAUL'S 
PULVERIZING  BARREL. 

[53.]     Paul's  Pulverizing  Barrel  is  a  happy  con- 
ception, the  value  of  which  is  not  yet  generally  ap- 
preciated.    It  is  most  advantageously  used  to  fol- 
3* 


58 


TESTING    AND    WORKING 


low  a  battery  which  crushes  dry  through  a  screen 
of  about  30  meshes  to  the  linear  inch,  and  is  excel- 
lently adapted  to  the  preparation  of  silver  ores  for 


mr 


raw  working,  or  of  roasted  ores  for  amalgamation 
in  machines  which  do  not  grind,  as  barrels.  As 
rock  is  used  to  grind  rock,  there  is  less  wear  of 


SILVEB    OEES.  59 

iron  than  in  other  iron  pulverizers,  a  point  which  is  of 
great  advantage  when  treating  ores  by  those  pro- 
cesses which  depend  on  the  use  of  solutions  of  cop- 
per, except  indeed,  in  those  cases  of  copperous  ores, 
in  which,  as  already  explained,  a  certain  quantity 
of  iron  may  be  used  with  advantage.  There  is  an 
impression  among  some,  that  this  machine  works 
very  slowly,  but  I  think  this  judgment  has  been 
formed  without  due  consideration  of  the  work  done. 
A  machine  which  will  take  10  tons  of  ore,  as  it 
comes  through  a  30-mesh  screen,  and  will  pass  it 
all  through  a  screen  of  120  meshes  to  the  linear 
inch  in  24  hours,  using  only  4-horse  power  to  do 
it,  performs  an  enormous  work,  and  this,  I  am  told 
by  disinterested  parties,  is  what  Paul's  barrel  does. 

If  coarser  screens  were  used  it  would  of  course 

• 

work  faster,  but  the  unprecedented  fineness  of  the 
screens  preferred  by  Mr.  Paul  in  working  'gold 
ores,  is  justified  by  the  increased  yield  of  the  ore. 
In  treating  silver  ores  this  extreme  degree  of  fine- 
ness might  not  be  required;  it  is  a  point  to  be  reg- 
ulated by  trial — that  which  is  on  the  whole  most 
profitable  being  the  best. 

I  wish  it  to  be  distinctly  understood,  that  in 
speaking  of  Paul's  pulverizer,  I  do  not  mean  Paul's 


60  TESTING   AND   WORKING 

dry  amalgamation  process,  which,  though  it  seems 
to  be  a  good  thing  for  gold,  is  not  yet  proved  to  be 
so  for  silver,  as  the  two  metals  exist  in  a  totally 
different  condition  in  ores. 

PULVERIZING  BARREL. 

[54.  j  A  pulverizing  barrel  may  be  made  of  wood, 
not  to  discharge  continuously  like  Paul's,  which 
also  feeds  itself,  but  to  work  by  charges  It  is 
made  like  the  amalgamating  barrel,  and  lined  in 
same  way.  The  ore  is  coarsely  crushed  before 
being  put  in;  and  a  quantity  of  small  iron  balls,  or 
pieces  of  hard  rock,  are  put  in  with  it.  A  proper 
adjustment  of  the  speed  with  which  the  barrel  ro- 
tates, causes  the  ore  and  balls  to  roll  over  with  a 
grinding  action,  without  much  wear  of  the  barrel. 
A  grating  keyed  in  the  bunghole  of  the  barrel, 
when  discharging,  retains  the  balls,  and  allows  the 
pulverized  ore  to  come  out.  The  barrel  may  be 
mounted  on  a  wooden  shaft  passing  clear  through, 
and  with  broad  bands  of  iron  on  the  ends  for  jour- 
nals, and  friction  rollers  under  them;  or  it  may  be 
arranged  in  any  of  the  ways  described  for  amal- 
gamating barrels,  omitting  of  course  the  hollow 


SILVER   ORES.-^A 

?>> 
^V^* 

journals  for  steam,  and  the  precautions  regarding 
iron  inside,  both  of  which  are  needless/  Y\ 

KENDALL'S  BATTERY. 

[55. 1  Kendall's  battery  is  another  recent  inven- 
tion, designed  for  small  operations,  which,  like 
Crocker's,  is  ready  for  use  when  bought.  It  can 
strike  any  required  number  of  blows  per  minute, 
but  has  no  springs.  I  should  think  it  a  good 
machine  for  small  operations.  [For  cut  of  this 
Battery  see  next  page.] 

NOICES'  PULVERIZER. 

1 56.  |  Noices'  pulverizer  is  a  queer  looking  ma- 
chine, in  which  the  rolling  action  of  the  Chili  mill 
is  combined  with  the  grinding  of  the  arrastra.  It 
seems  simple  and  efficient,  is  worked  with  water, 
and  though  designed  especially  for  crushing  and 
amalgamating  gold  rock,  would  work  well  in  treat- 
ing silver  ore  without  roasting.  From  this  machine 
I  have  derived  the  idea  of  a  cheap  rock  breaker,  or 

grinder,  now  to  be  described. 

4 


TESTING   AND    WORKING 


SILVER    ORES. 


63 


A  CHEAP    ROCK  BREAKER. 


[57.]  In  the  above  cut,  a,  is  an  inclined  table, 
made  of  one  or  more  pieces  of  rock,  enclosed  by  a 
low  wall  of  rocks  or  wooden  lags.  On  the  table 
rests  a  mass  of  rock  b,  which  is  connected  by  the 
iron  rod  c,  with  the  crank  d;  another  iron  rod  e, 
also  fastened  into  the  rock  b,  passes  through  a 
slot  in  the  post/1.  The  ore  to  be  broken  is  thrown 
upon  the  table  in  front  of  the  moving  rock,  which, 
by  the  rotation  of  the  crank  in  the  direction  of  the 
arrow,  is  lifted  and  drawn  forward  over  the  ore.  As 
the  crank  continues  its  rotation,  the  weight  of  the 
rock,  and  the  sliding  movement  imparted  to  it,  crush 


64  TESTING    AND    WORKING. 

the  ore  beneath  it,  and  cause  it  gradually  to  work 
out  at  the  lower  end  of  the  table,  when  it  may  be 
transferred  to  a  pulverizing  barrel,  or  sifted,  and 
the  coarser  part  reground  in  the  machine.  This  is 
merely  a  suggestion,  and  improvements  will  doubt- 
less be  made  by  intelligent  miners. 


AMALGAMATORS. 


[58.]  The  man  who,  though  poor 'in  pocket,  has 
rich  ore,  need  not  despair  of  getting  along,  if  he 
has  energy  and  some  ingenuity.  A  five  gallon 
beer  barrel  will  make  an  admirable  amalgamator 
for  50  pounds  of  ore,  which,  if  worth  $500  per  ton, 


will  yield  as  much  money  as  a  ton  of  Comstock 
ore  at  $12.50  per  ton.  A  10  gallon  barrel  will  suf- 
fice to  extract  the  same  sum  from  100  pounds  of 
$250  ore,  and  either  of  these,  or  even  a  larger  cask, 
may  be  mounted,  as  follows: 


66  TESTING   AND    WORKING 

Find  the  centre  of  each  head,  and  cut  a  hole, 
three  inches  square  for  the  smallest  barrel,  and 
large  in  proportion  for  other  sizes.  Make  a  wood- 
en shaft  to  fit  tightly  in  the  holes,  and  long  enough 
to  form  journals  at  each  end.  On  one  end  fix  a 
crank,  and  in  the'  center  of  the  other  bore  a  f  inch 
hole,  far  enough  to  reach  inside  the  barrel  when 
the  shaft  is  in  place,  and  connecting  with  a  cross 
hole  through  the  shaft,  so  as  to  communicate  with 
the  interior  of  the  barrel.  Put  the  shaft  in  its 
place  through  the  barrel,  and  enlarge  the  bung- 
hole,  either  round  or  square,  and  make  a  bung  to 
fit.  Mount  the  barrel  on  supports,  just  as  you 
would  a  windlass.  Next,  get  a  tin  boiler,  have  the 
cover  soldered  on,  and  an  inch  hole  made  in  it,  to 
pour  water  in  with  a  funnel.  Next  get  a  piece  of 
J-inch  gas  pipe  with  a  stop-cock  in  the  middle,  and 
a  flange  made  of  a  collar  soldered  on  two  inches 
from  one  end,  and  solder  the  other  end  into  the 
boiler  near  the  top;  and  it  will  be  best  to  have  two 
small  faucets  set  in,  one  six  inches  from  the  bottom 
of  the  boiler,  the  other  higher  up,  for  try  cocks  to 
show  how  much  water  you  have.  The  hole  in  the 
top  must  not  be  plugged,  but  an  iron  or  lead 
weight  must  be  used  to  close  it;  if  the  hole  be  one 


SILVER   ORES.  67 

inch  diameter,  the  weight  may  be  from  one  to  two 
pounds;  this  forms  a  safety  valve.  Mount  the 
boiler,  with  a  fire  place  below  it,  so  that  the 
steam  pipe  may  enter  the  hole  in  the  end  •  of  the 
barrel  shaft  as  far  as  the  flange.  Get  from  5  to  20 
pounds  of  copper,  in  the  form  of  balls,  from  ^  to*l 
inch  in  diameter,  or  little  bars,  or  pieces  of  any 
kind,  not  too  thin  so  as  to  break  up  when  used; 
pieces  of  J-inch  sheet  are  good  for  a  very  small 
operation.  When  the  barrel  is  charged  with  ore, 
and  a  little  water,  let  the  steam  from  the  boiler 
pass  into  it  before  putting  in  the  bung,  to  drive 
out  the  air,  then  put  the  bung  in  securely,  and 
tie  a  cord  round  the  barrel  to  keep  it  in.  Turn 
the  barrel  by  hand  or  foot,  by  dog,  squaw,  china- 
man, horse,  water  or  steam  power,  and  you  have  a 
perfect  amalgamator  for  working  Aaron's  process. 

[59.]  The  ore  may  be  ground  in  any  of  the 
machines  described  for  that  purpose,  or  if  very 
rich,  even  in  a  large  hand  mortar,  with  the  pestle 
attached  by  a  cord  to  a  spring  pole.  A  wash  tub 
fitted  with  some  simple  kind  of  stirrer,  will  answer 
for  a  separator.  Work  your  ore  precisely  as  di- 
rected, using  bluestone  instead  of  dichloride  of 


68  TESTING   AND   WORKING 

copper,  unless  you  choose  to  make  the  dichloride 
in  your  porcelain-lined  pot. 

[60.]  I  have  supposed,  thus  far,  that  you  have 
already  tested  the  ore,  according  to  the  directions 
given,  and  found  it  to  yield  satisfactorily;  but  the 
same  barrel,  without  the  boiler,  will  answer  for 
working  roasted  ore,  only  instead  of  the  pieces  of 
copper,  it  is  best  to  use  scraps  of  iron,  in  quantity 
from  10  pounds  upward,  according  to  size  of  bar- 
rel. If  the  ore  must  be  roasted,  you  may  build 
with  rocks  and  mud,  a  little  furnace  similar  to  that 
described  hereafter,  but  simpler,  and  as  each 
square  foot  of  hearth  will  take  about  10  pounds  of 
ore,  a  hearth  four  feet  square  will  be  ample  for 
something  over  100  pounds.  A  barrel  for  Aaron's 
process,  to  contain  1-J  tons  of  ore,  is  5J  feet  long 
by  4J  feet  diameter  inside,  and  is  mounted  either 
on  journals,  or  on  rollers.  The  ordinary  Freiberg 
barrel  answers  if  the  journals  be  made  hollow  to 
admit  steam.  In  calculating  the  size  of  a  barrel 
for  working  unroasted  ore,  I  allow  from  20  to  25 
cubic  feet  for  each  ton  of  ore,  and  it  must  be  re- 
membered that,  owing  to  the  necessity  of  admit- 
ting steam  at  the  center,  the  barrel  can  never  be 


SILVER   ORES.  69 

quite  half  filled,   so  that  a  barrel  of  100  cubic  feet 
capacity  would  contain  about  2  or  2J  tons. 

The  barrel  is  lined  with  blocks,  cut  from  3-inch 
plank,  and  so  placed  that  the  grain  of  the  wood  is 
vertical  to  the  axis  of  the  barrel.  These  blocks 
are  cut  at  the  saw  mill,  and  before  being  put  in  are 
bevelled  at  the  sides  with  a  jack  plane,  to  suit  the 
circle  of  the  barrel,  but  the  backs  need  not  be 
rounded,  nor  is  any  nicety  required  in  the  work, 
but  the  bevel  should  be  too  much,  rather  tlian  too 
little.  Mechanics  are  too  apt  to  make  a  bad  job 
of  lining  a  barrel,  simply  because  they  do  the  work 
too  well;  instead  of  requiring  close  joints,  it  is 
better  if  the  blocks  are  somewhat  rough,  and 
warped  sideways,  so  that  in  bevelling  them  the 
warp  should  not  be  taken  off  with  the  plane,  and 
in  placing  them  they  should  be  put  with  two  bulg- 
ing sides,  or  two  hollow  sides  together,  which 
leaves  room  for  swelling  without  bursting  the  bar- 
rel, or  making  the  lining  bulge  inward,  leaving  a 
space  behind  it  to  get  full  of  amalgam.  I  have 
known  $3,000  of  amalgam  to  be  taken  from  be- 
hind the  lining  of  a  single  barrel,  which  was  lined 
by  a  good  mechanic ;  and  this  accumulation  is  very 
troublesome  and  injurious,  by  destroying  the  equi- 


70  TESTING   AND   WORKING 

libriuin  of  the  machine.  In  putting  in  a  lining,  it 
is  only  necessary  to  nail  one  piece  here  and  there, 
just  to  keep  them  in  place  till  the  circle  is  complete, 
when  they  key  themselves,  and  when  wet  swell 
tight.  When  worn  through,  the  lining  is  removed 
and  a  new  one  put  in,  for  which  purpose  the  bar- 
rel is  furnished  with  a  manhole  in  the  head,  which 
is  closed  with  a  door,  just  as  in  a  steam  boiler,  but 
made  of  wood. 

The  staves  are  made  of  3  x  4  scantling,  not 
rounded  outside  or  inside,  the  heads  of  3-inch 
plank  of  the  hardest  pine.  There  are  four  hoops 
of  3  x  -J  inch  iron,  with  lugs  and  bolts  to  set  them 
tight.  The  lining  is  two  inches  thick,  and  before 
putting  it  in,  about  20  pounds  of  roofing  petro- 
leum is  melted,  and  poured  into  the  barrel,  into 
which  steam  is  admitted  by  the  hollow  journal, 
and  it  is  put  in  motion.  The  petroleum  soaks 
into  the  staves,  and  makes  the  barrel  steam  tight; 
the  lining  is  then  put  in.  For  the  purpose  of 
charging  and  discharging,  there  is  a  6-inch  bung 
hole,  and  a  bung  which,  when  in  place,  comes  flush 
with  the  lining  inside,  and  is  secured  by  an  iron 
hasp.  A  small  plug  in  the  end  of  the  barrel  serves 
for  taking  out  a  sample  of  pulp  for  examination 
when  required. 


/V     f  &p 

SILVER    ORES.  --f^>  iPl 

0*,%,%,      ** 


[61.]     The  copper  used  is^a  thMfi£jjp,of  ba4&>  j  . 
or  small  bars  of  not  more  than  one-  go 


The  balls  are  cast,  and  the  bars  are  sometimes  ^  * 
from  long  round  cast  bars,  but  flat  pieces,  either 
cast,  or  cut  from  J-inch  rolled  sheet,  are  to  be 
preferred,  as  exposing  more  surface  to  a  given 
weight.  When  the  pieces  become  so  small  as  to 
be  with  difficulty  separated  from  the  amalgam, 
they  are  first  passed  through  the  retort,  to  recover 
adhering  quicksilver,  and  then  remelted  and  cast. 
Rolled  copper  retains  quicksilver  on  the  surface 
only,  but  that  which  is  cast  sometimes  become8 
permeated  throughout  with  it.  The  quantity  of  cop- 
per used  varies  with  the  richness  of  the  ore,  a  great 
excess  giving  rise  to  a  poor  quality  of  bullion,  from 
the  fact  that  more  is  worn  off  than  can  be  consum- 
ed in  the  chemical  action.  About  50  square  feet  of 
copper  surface  answers  generally  for  a  barrel  of  \\ 
tons  capacity. 

[62.  |  One  way  of  preventing  the  mechanical 
wear  of  the  copper,  is  to  use  only  so  much  quick- 
silver as  to  form  a  hard  amalgam,  which  then  ad- 
heres to  the  copper.  This  method  was  practiced 
in  one  of  the  mills  at  Benton,  and  was  supposed  to 


72  TESTING   AND   WORKING 

economize  quicksilver,  though  I  beg  leave  to 
doubt  this,  not  on  theoretical  grounds  alone,  but 
because  I  did  not  find  it  so  in  my  mill.  The 
actual  consumption  of  copper,  in  proportion  to 
silver  extracted,  has  not  been  determined. 

[63.]  There  are  three  ways  to  use  the  quicksil- 
ver in  this  process:  Firstly — at  least  one  flask  is 
used  for  each  $100  of  silver  in  the  barrel.  This  gives 
a  liquid  amalgam,  which  comes  out  free  from  sand, 
and  the  copper  balls  are  simply  coated  with  quick- 
silver. Secondly — only  enough  is  used  to  form 
hard  amalgam,  which  sticks  to  the  copper,  as  al- 
ready stated,  making  it  necessary  to  put  the  balls 
into  a  pot  of  quicksilver  to  get  it  off,  and  yielding 
an  amalgam  which  is  mixed  with  sand.  Thirdly — 
so  little  is  used  that  the  copper  balls  come  out  free 
from  quicksilver  and  amalgam,  and  the  latter  floats 
through  the  pulp  in  the  form  of  gray  flakes  and 
pellets.  The  last  is  probably  the  best,  as  it  leaves 
the  surface  of  the  copper  free,  so  that  the  ore 
comes  in  direct  contact  with  it,  and  the  whole  of 
the  quicksilver  comes  out  of  the  barrel  with  the 
pulp,  but  it  requires  the  use  of  a  wooden  vessel, 
intermediate  between  the  barrel  and  the  separator, 


SILVER   ORES. 


73 


in  which  the  floating  amalgam  may  be  gathered  by 
means  of  an  additional  quantity  of  quicksilver,  for 
as  already  remarked  the  iron  bottom  of  the  sep- 
arator causes  the  production  of  copper  amalgam. 

[64.]  I  have  used  a  barrel  in  which  the  copper 
was  fixed,  in  the  form  of  one  inch  bars,  of  which 
there  were  20,  extending  the  whole  length  of  the 
barrel,  and  fixed  at  the  distance  of  one-half  inch 
from  the  staves.  It  depends  on  how  the  quicksil- 
ver is  used  whether  the  amalgam  sticks  to  the  bars 
or  not.  This  barrel  needs  no  lining,  as  the  cop- 
per, being  fixed,  does  not  wear  it.  The  entering 
a  barrel  to  line  it,  to  fix  the  copper,  or  to  remove 
amalgam,  is  a  disagreeable  job,  and  when  it  must 
be  done,  considerable  time  is  consumed  in  cooling 
it  for  the  workman  to  enter.  To  avoid  this,  and 
other  inconveniences  of  the  barrel,  I  have  invented 
a  machine  which  I  will  describe  after  I  have  fin- 
ished about  barrels. 

[65.]     The    following    drawing    represents   the 

Freiberg  barrel  used  for  roasted  ore  at  Palmetto, 

Nevada.       By   drilling   through   the    journals,    or 

having   them  cast   larger  and  hollow,   and   lining 

4 


74 


TESTING    AND    WORKING 


with  blocks  as  directed,  this  barrel  will  answer  for 
working  unroasted  ore;  its  capacity  without  lining 
is  one  ton  of  ore. 


c 

'A; 

j 

c 

A 

A 

A 

I  — 

A. 

0 

A  $ 

I 

B     D 

D 

D 

C 

xj 

FREIBERO     BARREL. 
,  hoops.    B,  journal.    C  and  B,  iron  flange. 


bolts. 


[66.]  A  cheap  barrel  is  made  as  follows  :  a  3-inch 
square  bar  of  iron  of  the  proper  length,  with  jour- 
nals six  inches  long  turned  on  the  ends,  is  bored 
at  each  end,  precisely  as  directed  for  the  wooden 
shaft  of  the  small  barrel.  This  iron  shaft  passes 
through  the  barrel,  and  is  secured  by  cast  flanges 
bolted  to  the  barrel  heads.  The  flanges  are  cast 


SILVER    ORES.  75 

in  two  parts,  with  a  strong  hub  through  which  the 
shaft  passes,  and  the  two  sections  are  fastened  to- 
gether by  means  of  a  rib  along  each  edge  of  the 
joint,  through  which  bolts  pass.  This  is  not 
absolutely  necessary,  however.  The  square 


FLANOE. 

x,  bolt  holes,    y,  holes  for  lag  bolts  running  into  head  of  barrel. 

opening  in  the  hub  is  slightly  smaller  than 
the  shaft,  and  is  so  placed  that  the  division 
of  the  two  sections  of  the  flange  crosses  it  diag- 
onally. The  places  for  the  flanges  being 


76  TESTING   AND   WORKING 

accurately  marked  on  the  shaft,  they  are 
secured  by  a  wrought  iron  band  shrunk  on  to  the 
hub.  The  barrel  heads  are  then  fastened  to  the 
flanges  by  bolts  passed  from  within,  with  the  nuts 
outside,  and  the  heads  supported  by  3-inch  coun- 
tersunk cast  washers,  sunk  flush  into  the  wood. 
These  are  protected  by  a  covering  of  putty,  (better 
than  white  lead,)  or  a  mixture  of  linseed  oil  and 
dust,  and  further  by  a  wooden  cap  soaked  in  hot 
petroleum,  with  which  the  whole  inside  of  the  head 
is  also  painted.  The  shaft  being  mounted,  the 
heads  are  turned  true,  the  iron  shaft  encased  with 
wood  soaked  with  petroleum,  and  having  in  it  holes 
corresponding  to  the  cross  holes  in  the  iron,  lined 
with  short  pieces  of  pipe  tapped  into  the  iron  shaft 
to  keep  the  steam  from  the  wood;  and  a  wooden 
cap,  opening  horizontally,  is  pinned  on  over  each 
hole  to  keep  the  pulp  from  falling  in  The  staves, 
which  should  be  grooved  and  tongued  for  a  lined 
barrel,  are  then  put  on,  and  nailed,  to  hold  hold 
them  until  the  bands  are  on  and  tightened  with 
the  draw  bolts,  after  which  the  barrel  is  treated 
with  hot  petroleum  and  steam,  as  already  describ- 
ed, and  is  then  ready  for  lining.  Some  use  a  stuff- 
ing box  in  the  end  of  the  shaft  where  the  steam 


SILVER   ORES. 


77 


pipe  enters,  but  a  simple  flange  on  the  pipe  is  suf- 
ficient. It  is  important  that  no  iron  work  be  left 
exposed  inside  the  barrel,  as  the  action  of  the 
chemicals  would  soon  destroy  it. 

[67.]  The  trough  or  launder  into  which  the 
barrel  is  discharged,  and  which  conveys  the  pulp 
to  the  separator,  is  arranged  in  any  convenient 
way,  the  best  being  that  in  use  at  Freiberg,  as  seen 


in  the  cut,  the  bottom  being  made  of  a  solid  tim- 
ber, and  the  sides  of  matched  boards,  and  extend- 
ing under  any  number  of  barrels,  mounted  end  to 
end.  At  some  convenient  part,  between  the  bar- 
rels and  the  separator,  is  a  pot  to  retain  the  quick- 
silver as  already  said. 


78 


TESTING   AND   WORKING 


1       • a     t  ...    v^LUU.. 

'••I . -  \\\VQ?- I'-.xV v  \\M >\  \\\\\\-.-t '-  V  -\  i:  ; 


>M\\\\\^NtS\\NX\\\NK 


a,  stave,    b,  lining,    c,  iron  shaft,    d,  cast  flange,     e,  wrought  band. 
/,  manhole,    g,  cap  over  steam  hole. 


o 


SILVER    ORES. 


79 


[68.]  A  barrel  of  any  required  capacity,  even  up 
to  50  tons,  may  be  mounted  on  rollers  as  in  the 
sketch.  The  rollers  work  on  a  cast,  circular 
flanged  rail,  which  surrounds  the  barrel.  Mr.  GL 
F.  Deetken  has  built  such  a  barrel,  with  which  to 
work  copper  solutions,  which  is  12  feet  long  by  8 
feet  diameter;  it  is  moved  by  a  screw  working  into 
a  circular  rack  surrounding  the  barrel.  This  bar- 
rel may  be  charged  while  in  motion,  through  the 
circular  opening  in  the  end,  steam  being  admitted 
at  the  other  end. 

AARON'S  AMALGAMATOR. 

[69.]  Figure  1  is  a  perspective  view  of  my  de- 
vice. Fig.  2  is  a  transverse  vertical  section. 

A  is  a  vessel  of  cylindrical  or  nearly  cylindrical 
form,  of  which  the  lower  portion  is  fixed  and  the 
upper  portion  is  movable  as  a  lid  or  cover,  and 
within  which  is  mounted  a  paddle  wheel,  B,  with 
oblique  floats  c  c  c,  and  which  is  provided  with 
openings  d  d,  in  each  end,  as  shown.  The  wheel 
rotates  in  close  proximity  to  the  bottom  of  the  ves- 
sel A,  so  as  to  pass  through  a  mass  of  pulp,  and 
dip  in  a  bath  of  mercury  contained  therein. 


80  TESTING    AND    WORKING. 

I  prefer  to  construct  the  vessel  in  an  oval  form 
with  its  longest  diameter  in  a  horizontal  plane,  so 

Fig.  1. 


that  a  space  will  be  left  in  front  and  rear  of  the 
wheel,  while  it  moves  close  to  the  bottom  and  top 
of  the  wheel  in  its  rotation. 

The  floats  c  c  c,  of  the   paddle  -  wheel   may  be 
made  of  any  suitable  material,  but  preferably  of 


SILVER    ORES. 


81 


wood,  faced  with  copper  on  the  inner  surfaces,  and 
the  wheel  is  secured  upon  a  shaft,  E,  which  bears 
upon  opposite  sides  of  a  hinged  frame,  F.  This 
frame,  F,  is  so  connected  with  the  vessel,  A,  by 
means  of  its  hinges  as  to  admit  of  its  being  lifted 
at  one  end  so  as  to  raise  the  paddle-wheel  out  of 
the  lower  half  of  the  vessel.  The  upper  half  or 

Fig.   2. 


lid  of  the  vessel  A,  is  also  hinged  concentrically 
with  the  frame  F,  and  may  be  raised  together 
therewith,  or  separately.  The  vessel  A,  may  be 
constructed  of  iron,  or  in  cases  where  the  pres- 
ence of  metallic  iron  is  objectionable,  of  enameled 
iron,  or  of  wood,  or  other  suitable  substance. 
4* 


82  TESTING    AND    WORKING    SILVER    ORES. 

Motion  is  given  to  the  paddle-wheel  B,  by  means 
of  a  belt  and  pulleys  revolving  concentrically  with 
the  frame,  so  that  the  rotation  of  the  paddle 
wheel  is  not  interfered  with  by  raising  it  to- 
gether with  the  frame. 

The  vessel,  A,  is  provided  with  an  opening,  h,  in 
the  upper  part  or  cover,  and  has  a  plug,  i,  in  the 
lower  part,  to  facilitate  the  introduction  and  dis- 
charge of  the  ore  to  be  treated. 


THE  SEPARATOR, 


[70.]  The  ordinary  separator  is  not  suitable  for 
use  in  connection  with  barrels,  especially  when 
treating  unroasted  ore  by  Aaron's  process.  The 


Fig.   1. 


kind  I  prefer  for  this  purpose  is  shown  in  Fig.  1, 
and  consists  simply  of  a  wooden  tub  six  feet  in 
diameter  and  four  feet  deep,  in  the  bottom  of  which 
is  an  iron  annular  disc,  raised  an  inch  and  a  half 
from  the  bottom  of  the  tub  by  a  smaller  disc  of 


84 


TESTING   AND    WORKING 


wood  under  it,  which  leaves  the  iron  disc  project- 
ing about  two  inches.  The  muller  is  made  of 
scantling  in  the  manner  shown  in  Fig.  2,  and  the 
arms  are  short,  not  reaching  to  within  six  inches  of 
the  side  of  the  tub. 

Fig.  2. 


The  mortises  are  arranged  with  keys,  so  that  the 
muller  can  be  clamped  tightly  to  the  square 
wooden  shaft,  the  lower  end  of  which  runs  on  a 
low  wooden  cone  having  a  core  of  mountain  ma- 
hogany, and  rising  from  the  bottom  of  the  tub  up 
through  the  iron  disc  to  a  height  of  several  inches. 
The  upper  end  of  the  wooden  shaft  is  connected 
with  a  short  iron  shaft,  working  in  boxes  attached 


SILVEK    ORES.  85 

to  the  framing,  and  carrying  the  pulley  or  gearing. 
The  wooden  shaft  should  be  arranged  to  slide  upon 
the  iron  portion,  so  that  the  muller  may  drop  as  it 
wears  away,  or  may  be  raised  with  a  lever  in  case 
of  accident.  The  shorter  the  arms  are  the  higher 
speed  is  used,  and  it  should  be  such  that  the  sand 
and  particles  of  quicksilver  are  kept  in  continual 
suspension,  till  the  latter,  gathering  together  in  a 
mass,  settles  into  the  annular  space  around  the 
iron  disc,  where  it  remains  undisturbed,  while  the 
sand  remaining  in  suspension  is  drawn  off  with  the 
water  by  successive  plug-holes  in  the  side  of  the 
tub.  Any  pieces  of  rock  or  copper,  etc.,  which 
may  accidentally  find  their  way  into  the  machine 
lodge  under  the  projecting  edge  of  the  iron  disc. 

The  pulp,  as  discharged  still  warm  from  the  bar- 
rel, always  contains  copper  dichloride  in  solution. 
By  working  it  for  an  hour  or  two  before  adding 
water,  in  a  separator  with  an  iron  bottom,  which 
is  scoured  by  a  wooden  muller,  a  copper  amalgam 
is  formed,  thus  preventing  a  large  loss  of  quicksil- 
ver. It  is  for  this  reason  that  the  bulk  of  fine 
amalgam  from  the  barrel  is  not  allowed  to  enter 
the  separator,  where  it  would  become  mingled 
with  the  base  amalgam  there  produced. 


RETORTS. 


[71.]  A  small  retort  is  improvised  by  cutting 
the  top  off  a  quicksilver  flask,  the  cover  being 
formed  of  the  upper  part  of  another  flask,  into 
which  is  screwed  a  piece  of  pipe  about  four  feet 
long,  curved  near  where  it  enters  the  cover,  so  as 
to  incline  downwards  when  the  retort  is  in  work. 
The  cover  is  stretched  on  the  horn  of  the  anvil  so 
as  to  overlap  the  body  of  the  retort,  and  an  iron 
band  is  slipped  over  the  joint,  which  is  well  plas- 
tered with  a  stiff  paste  made  of  sifted  ashes  and 
water,  with  which  also  the  inside  of  the  retort  is 
painted  before  putting  the  amalgam  in.  The  pipe 
is  wrapped  with  sacking,  on  which  water  drips 
continually  from  a  barrel.  The  end  of  the  pipe 
must  not  dip  into  the  water  in  the  receiving  pot, 
as  there  is  danger  of  an  explosion  from  the  water 
being  drawn  up  the  pipe  into  the  retort.  A  retort 
should  not  be  more  than  two-thirds  filled  if  the 
amalgam  is  fine,  nor  more  than  half  when  much 


SILVER    ORES. 


87 


base  metal  is  present.     It  is  a  good  plan  to  have  a 
piece  of  stout  wire  or  nailrod  passing  through  the 

ROASTING     FURNACE. 


a,  hearth,  b,  bridge,  c,  fire-place,  d,  flue,  e,  stack.  /,  working 
door,  g,  discharging  door,  h,  binder,  i,  hopper,  k,  iron  to  support 
working  door.  I,  a  dust  chamber  into  which  the  flues  open,  and  which 
being  drawn  into  a  square  above  the  flues  becomes  the  stack,  e.  m, 
roller. 

pipe  into  the  retort,  with  which  the  operator  may 
assist  in  the  expulsion  of   any  dirt  which  may  pass 


88  TESTING    AND    WORKING 

over  and  obstruct  the  pipe.  The  fire  is  made  on 
the  top  of  the  retort  first,  and  the  operation  must 
never  be  hurried,  but  allowed  to  proceed  gently 
till  nearly  all  the  quicksilver  has  passed  over,  when 
the  heat  may  be  raised  to  a  dark  red,  and  so  kept 
till  no  more  quicksilver  can  be  got.  The  retorted 
spongy  silver  may  be  sent  to  the  mint,  without 
being  first  melted  into  bars.  Explosions  only  oc- 
cur through  ignorance  or  carelessness.  If  there  is 
good  reason  to  think  that  the  pipe  is  stopped,  as 
sometimes  happens  through  the  swelling  of  the 
amalgam,  when  overcharged,  or  if,  as  sometimes 
happens  with  cast  retorts,  quicksilver  is  seen  es- 
caping from  a  crack,  the  fire  must  instantly  be 
drawn,  or  the  operator  must  emigrate. 

For  quantities  of  amalgam  up  to  200  pounds, 
cast  iron  pot  retorts  are  used;  beyond  that,  the 
cylindrical  or  D  patterns,  permanently  set  in  ma- 
sonry, and  provided  with  a  water  jacket  for  the 
pipe. 

1 72.  |  The  hoes  for  stirring  the  ore  are  16  feet 
long,  and  in  order  to  use  them  with  convenience, 
an  iron  roller  resting  on  bearings  built  into  the 
brickwork,  is  placed  before  the  working  door,  a 


SILVEB    ORES.  89 

little  above  the  level  of  the  hearth.  The  shank  or 
handle  of  the  hoe  is  best  made  of  gas  pipe,  all  but 
about  five  feet  next  the  head,  which  is  solid.  The 
head  or  blade  is  either  of  cast  or  wrought  iron,  and 
as  they  do  not  last  long,  several  spare  ones  are 
kept  on  hand.  There  must  always  be  several  hoes 
in  readiness  for  use,  so  that  they  may  be  changed 
when  too  hot.  A  fire  hook  is  also  necessary  for 
trimming  the  fire,  and  some  use  long-handled  iron 
spades  for  moving  the  ore  from  end  to  end  of  the 
furnace,  as  must  be  done  several  times  in  order 
that  all  may  be  equally  heated,  but  workmen  soon 
learn  to  do  this  with  the  hoe.  Bakes  with  cast  iron 
heads  are  also  sometimes  used,  as  they  are  more 
easily  drawn  through  the  ore  than  hoes,  but  the 
hoe  cannot  be  dispensed  with,  and  in  some  mills 
nothing  else  is  used. 

The  working  door  of  the  furnace  is  kept  open 
nearly  all  the  time  when  roasting,  but  is  closed 
when  required,  by  a  piece  of  boiler  iron,  cut  to  fit 
the  opening,  and  furnished  with  two  small  holes, 
about  four  inches  apart,  to  receive  the  prongs  of  an 
iron  fork  with  which  to  lift  it;  when  in  place  it 
rests  against  the  iron  strap,  K,  which  is  built  into 
the  opening,  and  forms  a  rabbet.  The  fire  door, 


90  TESTING    AND    WORKING 

and  that  at  the  back,  are  also  of  boiler  iron,  hung 
upon  pintles  set  in  the  masonry.  The  ashpit  opens 
on  the  opposite  side  from  the  fire  door,  which 
causes  the  heat  to  be  more  even  in  the  fire  place. 
The  dust  chamber  should  be  as  large  as  possible. 
It  is  a  good  plan  to  carry  the  flue  under  the  drier 
in  front  of  the  battery,  forming  a  dust-  chamber, 
and  using  the  waste  heat  from  the  furnace  to  dry 
the  ore  for  crushing .  The  draught  of  a  furnace 
must  not  be  too  strong,  but  just  enough  to  keep 
the  fumes  from  coming  out  of  the  open  door.  To 
regulate  the  draught  a  damper  is  provided,  which 
may  be  conveniently  placed  in  the  stack,  being  sim- 
ply a  piece  of  sheet  iron  turning  on  a  pivot,  just 
like  the  damper  in  a  stove  pipe. 

[73.  ]  The  main  body  of  the  furnace  may  be  built 
of  rocks  and  mud,  the  hearth,  or  sole,  walls  and 
arch,  of  brick;  those  in  the  sole  being  laid  on  a  bed 
of  sand.  The  bricks  in  the  arch  are  laid  end  up 
on  a  form  made  of  moist  sand,  which  is  drawn  out 
as  soon  as  the  work  is  done,  to  let  the  arch  settle 
as  it  dries,  for  which  reason,  also,  it  is  built  with 
a  little  more  spring  than  is  wanted.  In  addition 
to  the  longitudinal  curve,  it  is  slightly  arched 


SILVER    ORES.  91 

transversely.  In  the  walls  every  alternate  course 
should  be  headers  (bricks  laid  crosswise),  and  they 
must  be  supported  by  binders,  formed  of  strong 
posts  set  into  the  ground,  and  united  at  the  top  by 
an  iron  rod,  or  a  tie-beam,  across  and  above  the 
furnace.  If  the  ends  of  the  furnace,  forming  abut- 
ments to  the  arch,  are  built  very  heavy,  as  repre- 
sented, it  is  not  necessary  to  bind  it  lengthwise. 
Adobes  will  answer  for  building  a  furnace,  though 
they  will  not  last  so  long  as  bricks.  The  bridge, 
being  exposed  to  great  heat  and  hard  knocks,  is 
best  made  of  one  or  two  pieces  of  fire  stone,  or  of 
firebrick  mixture  beaten,  while  moist,  into  a 
mould;  but  common  bricks  answer  pretty  well. 

[74. )  In  a  much  smaller  furnace  the  walls  may 
be  made  of  a  concrete  of  mud  and  small  rocks,  and 
the  arch  of  adobe  material,  laid,  like  plaster,  on  a 
form  of  damp  sand  covered  with  paper.  The  plas- 
ter is  laid  on  two  inches  thick,  and  as  it  will  crack 
some  in  drying,  it  is  cut  through  with  the  trowel  in 
squares;  before  it  is  quite  dry  another  layer  is  put 
on,  and  so  on  till  it  is  thick  enough,  the  support- 
ing sand  being  drawn  out  as  soon  as  the  arch  will 
stand. 


92 


TESTING    AND    WORKING 


[75.]  I  have  given  these  details  about  the  fur- 
nace for  the  benefit  of  those  whose  situation  makes 
it  necessary  to  make  a  start  with  as  little  cash  out- 
lay as  possible;  but,  as  soon  as  circumstances  will 
allow,  I  strongly  advise  the  use  of  a  revolving 
cylinder— that  of  Bruckner  being  the  best  for  a 
small  operation. 

AARON'S    LEACHINO    APPARATUS,    No.     1. 
[Patent  to  be  applied  for.] 


a 


a  is  an  ordinary  leaching  vat;  b  is  a  wooden  vac- 
uum chamber;  c  and  d  are  pipes,  either  of  wood  or 
rubber,  furnished  with  stop-cocks;  e  is  a  precipitat- 
ing vat;  f  a  flannel  bag;  and  g  a  steam  pipe  con- 
necting with  a  boiler.  The  ore  being  placed  in  a, 
and  saturated  with  the  leaching  fluid,  (the  cock  in 
c  being  closed)  the  chamber  b  is  filled  with  steam, 


/'•  &\  <J  /J 

SILVER   ORES.      ff  ^*  ./ vv 

O       ^:/j         ^ 

the  air  being  expelled  through  d  w^c^Ti^(o^)en'  d  is*  /  ^ 
then  closed,  and  steam  shut  off,  when  eyeing /f^ii-, 

^•^  /  ^  \ 

ed,  a  vacuum  is  formed  in  b  by  condensation  of  the' ••>'*/ 
steam  with  which  it  was  filled.  The  pressure  of 
the  atmosphere  on  the  surface  of  the  fluid  in  a, 
forces  it  rapidly  through  the  bed  of  ore  into  b;  the 
cock  c  is  closed,  that  in  d  opened,  and  steam  again 
admitted  into  b,  and  by  its  pressure  forces  the 
solution  through  d,  into  e,  where  it  is  treated  with 
the  precipitating  agent,  and  when  clear,  is  drawn 
off  and  passed  again  to  «,  through  the  flannel  bag 
ft  by  which  any  floating  particles  of  precipitate  are 
retained.  The  bulk  of  precipitate  remaining  in  c, 
is  then  removed. 

[76.]     This  is  the  simplest  form  of  the  apparatus, 
and  is  given  merely  for  the  purpose  of  explanation. 

The  following  is  a  better  arrangement— 
] ,  2,  3,  4,  are  leaching  vats;  a  is  the  vacuum 
chamber.  No.  1  being  charged  with  ore,  and  the 
leaching  solution,  No.  2  is  also  filled  with  ore,  and 
the  solution  being  drawn  from  1,  by  means  of  the 
vacuum  chamber,  is  thrown  into  2,  while  1  is  sup- 
plied with  a  fresh  lot  of  the  solution  from  the  pre- 


94 


TESTING   AND   WORKING 


cipitating  vat,  not  represented  as  it  is  above  a.  In 
like  manner  the  solution  from  2  is  passed  to  3,  that 
from  1  to  2  again;  from  3  to  4;  again  from  2  to  3 
and  1  to  2;  then  Irom  4  to  the  precipitating  vat, 
from  3  to  4,  2  to  3  and  1  to  2  again.  The  silver  or 
other  metal  of  1  will  by  this  time  be  exhausted, 
and  it  is  emptied,  and  recharged  with  fresh  ore, 


and  the  next  discharge  from  4  is  passed  into  it, 
and  from  it  to  the  precipitator,  so  that  it  now  be- 
comes the  fourth  in  the  series,  the  former  No.  2 
becoming  No.  1;  and  so  the  operation  goes  on,  the 


SILVER    ORES.  95 

last  vat  charged  with  fresh  ore  being  always  No.  4 
of  the  series,  and  the  solution  from  it  being  passed 
to  the  precipitator  saturated  with  metal.  In  this 
way  a  concentrated  solution  of  metal  is  always  had 
for  precipitation,  the  metal  is  dissolved  rapidly  out 
of  the  ore  by  the  constant  movement  of  the  dissolv- 
ing solution,  and  the  finished  ore  is  quickly 
drained. 

[77.]  If  the  vacuum  vat  is  divided  vertically  in- 
to four  compartments,  by  cross  partitions  not  ex- 
tending to  the  top,  all  four  vats  can  be  drained  at 
once,  and  the  fluid  thus  passing  more  continuous- 
ly the  metal  will  be  dissolved  still  more  rapidly, 
for  it  is  well  known  that  sugar,  or  any  other  solu- 
ble substance,  is  dissolved  sooner  if  stirred  in 
water  than  if  left  at  rest;  and  still  sooner  if  placed  on 
a  filter  and  fresh  water  constantly  passed  through; 
so,  in  like  manner  the  metal  in  the  first  vat  is 
quickly  dissolved  by  the  constant  flow  of  fresh 
liquid,  while  the  inconvenience  of  operating  on  the 
weak  solution  which  comes  from  it  towards  the 
last,  is  obviated  by  passing  it  through  the  other 
vats,  and  lastly  through  one  containing  a  fresh 
charge  of  ore,  where  it  becomes  saturated.  In 


96  TESTING   AND    WORKING 

case  of  ores  requiring  several  distinct  leachings,  or 
washing  before  leaching,  there  may  be  two  or  more 
sets  of  vats,  mounted  on  trucks,  and  running  on 
tramways;  also,  as  many  vacuum  chambers.  The 
vats  then  replace  each  other  in  the  respective  sets, 
and  when  one  is  finished  it  is  wheeled  to  a  dump- 
ing place,  emptied,  and  after  being  recharged, 
takes  its  place  in  the  first  set.  Large  stationary 
vats  may  be  built  with  the  filters  inclined,  and  the 
exhausted  material  washed  out  with  a  stream  of 
water  from  a  hose.  Boasted  silver  ores  are  washed 
before  leaching  for  silver,  by  passing  through 
them  acidulated  water,  obtained  by  causing  the 
fumes  from  the  roasting  furnace  to  pass  through, 
or  in  contact  with  water,  either  by  means  of  a 
Cagriiardell's  condenser,  or  a  blower,  or  a  stack 
with  shelves,  rocks  or  coke  in  it,  which  are  kept 
wet  by  a  stream  of  water. 

[78.]  APPARATUS,  No.  2 — (Patent  to  be  applied 
for.)  I  have  devised  another  apparatus,  in  which 
the  dissolving  fluid  is  caused  to  circulate  contin- 
uously, either  through  the  same  vat,  or  through  a 
series,  by  means  of  centrifugal  iorce.  This  may 
be  used  for  extraction  of  gold  with  chlorinated 


SILVER   ORES. 


97 


water,  or  of  gold  and  silver,  together,  with  chlorin- 
ated brine.  The  following  diagram  shows  its  oper- 
ation : 


[79.]  The  leaching  tub  is  securely  bolted  to  the 
revolving  iron  table  a;  the  ore  is  seen  at  b,  occupy- 
ing the  annular  chamber  formed  by  the  circular 
partition  c,  and  cover  d.  The  partition  c  is  con- 
structed of  perforated  wood,  and  canvas,  so  that 
the  dissolving  fluid,  being  poured  into  the  central 
opening,  and  the  tub  being  made  to  rotate 
rapidly  by  a  belt  working  on  the  cone  pulley  /,  it 
is  driven  by  centrifugal  force  through  the  ore  6, 
into  channels  between  the  blocks  g,  and  reaching 
5 


98  TESTING   AND    WORKING 

the  sloping  side  of  the  tub  h,  flows  upward  and 
into  the  channel  iy  which  is  attached  to,  and  sur- 
rounds the  tub.  A  fixed  scoop  and  pipe  k,  dips 
into  this  revolving  channel,  and  the  fluid,  charged 
with  metal,  is  forced  up  through  the  pipe  k,  to 
which  is  attached  a  piece  of  rubber  tube  j,  and  is 
delivered  into  the  center  of  another  similar  ma- 
chine, or  a  precipitating  tank,  or  back  to  the  center 
of  the  tub  from  which  it  came,  to  pass  again 
through  the  ore.  The  cone  m,  is  simply  to  occupy 
a  portion  of  the  needless  space  in  the  tub. 

[80.]  When  the  ore  is  exhausted  and  drained, 
the  machine  is  stopped,  the  cover  d,  removed,  and 
the  tub  being  again  put  in  motion  the  ore  is 
scooped  out  of  the  annular  chamber  by  a  fixed 
scoop  not  shown  in  the  diagram.  The  speed  of 
rotation  is  regulated  as  required,  by  means  of  the 
cone  pulley. 


[81.]  The  sketch  represents  a  mill  for  working 
two  or  three  hundred  pounds  of  rich  ore  per  day. 
The  large  wheel  may  be  a  water  wheel,  or  tread- 
mill; the  pulverizing  barrel  a,  is  a  beer  or  wine 


SILVEB    ORES. 


99 


cask,  as  is  also  the  amalgamating  barrel  b;  the  sep- 
arator/, is  a  large  washtub.  Beneath  the  pulver- 
izing barrel  is  a  seive  c,  to  retain  the  balls  or  lumps 
of  rock,  the  ore  falling  into  the  box  d.  Under  the 
amalgamating  barrel,  which  is  driven  by  a  belt 

A    VERY    SMALL    MILL. 


from  a,  is  a  trough  e,  to  carry  the  pulp  to  the  sep- 
arator, which  is  worked  by  a  half -twisted  belt  from 
a  pulley  on  the  shaft  of  b.  The  boiler  for  heating 
the  barrel  is  not  represented.  In  a  larger  affair 
the  pulverizer  a,  may  be  replaced  by  a  small  arras- 
tra. 

Perhaps  the  best  way  to  utilize  a  very   small 


100  TESTING   AND    WORKING. 

power,  is  to  apply  it  all  to  one  part  of  the  process 
at  a  time.  Thus,  ore  may  be  crushed  for  several 
days  in  succession,  and  then  amalgamated  in  one 
day.  In  this  way  there  are  not  so  many  things  to 
attend  to  at  once,  which  is  one  of  the  difficulties 
of  a  small  mill;  of  course,  however,  the  machin- 
ery to  work  a  given  quantity  of  ore  per  day  must 
be  larger  than  when  it  is  all  used  at  once,  and  each 
machine  will  be  idle  a  part  of  the  time.  How- 
ever, where  only  two  or  three  tons  of  ore  are 
worked  per  day,  this  plan  must  be  adopted  to 
some  extent  in  order  to  use  a  roasting  cylinder  to 
advantage. 

The  power  of  two  chinamen,  working  turn  about, 
will  work  200  or  300  pounds  of  ore  a  day;  that  of 
two  common  horses,  400  to  500  pounds,  and  60 
miners'  inches  of  water,  or  about  100  cubic  feet 
per  minute,  on  a  30 -foot  overshot  wheel,  with  a 
small  battery  or  an  arrastra,  will  work  from  two  to 
three  tons  in  24  hours. 

[82.]  An  error  into  which  inexperienced  per- 
sons are  apt  to  fall,  on  first  starting  a  mill,  is  being 
needlessly  alarmed  at  the  small  yield  of  amalgam, 
and  the  disappearance  of  a  quantity  of  quicksilver, 


SILVEK   ORES.  101 

owing  to  the  retention  of  both  in  the  various  ves- 
sels through  which  it  passes.  Positive  results  can 
only  be  arrived  at,  after  a  run  of  several  days  or 
weeks,  by  a  thorough  clean  up,  when  the  dies  of 
pans  must  be  lifted,  and  the  lining  of  barrels  re- 
moved. An  examination  of  the  tailings,  by  pan- 
ning, will  show  whether  much  quicksilver  is  being 
lost  mechanically;  and  as  a  chemical  loss  is  usually 
accompanied  by  granulation,  and  consequent  me- 
chanical loss,  or  at  least  a  difficulty  in  "settling," 
and  the  appearance  of  white  or  brown  powder  in 
the  tailrace,  a  careful  examination  will  afford  a 
good  indication  of  the  actual  loss.  An  assay  of  a 
true  sample  of  the  tailings  compared  with  the  value 
of  the  ore,  will  at  any  time  indicate  the  percentage 
to  which  the  ore  is  being  worked.  The  best  way  I 
know  of  to  take  a  sample  of  tailings,  is  to  take  a 
little  pulp  from  each  pan  or  barrel,  as  it  is  being 
discharged,  then,  after  thoroughly  mixing  the  gen- 
eral sample,  take  a  small  portion  in  a  saucer,  and 
carefully  pan  it  into  a  vessel  of  water,  retaining 
all  the  amalgam  in  the  saucer.  After  the  water 
has  settled  clear,  pour  it  off  as  far  as  possible  with- 
out losing  any  earthy  matter,  dry  the  residue  and 
assay  it.  The  result  will  at  least  not  be  too  high, 


102  TESTING   AND   WORKING 

because  the  sample  being  taken  before  the  pulp 
entered  the  separator,  it  will  be  richer  than  the 
final  tailings  by  as  much  as  is  extracted  by  the 
separator.  However  the  error  is  on  the  right  side, 
for  no  one  who  thinks  he  is  doing  well  will  grum- 
ble at  finding  that  he  is  doing  better  than  he  sup- 
posed. 

[83.]  I  will  now  describe  an  invention  which  I 
have  made,  to  replace  the  settling  tank  in  a  wet- 
crushing  mill,  which  will  obviate  twice  handling 
the  ore,  once  to  remove  it  from  the  tank,  and  again 
to  put  it  into  the  pans.  This  apparatus  has  also  the 
advantage  of  retaining  all  the  slimes,  together  with 
the  sandy  portion  of  the  pulp,  a  point  which  mill- 
men  will  appreciate,  and  it  may,  in  addition,  be 
arranged  so  as  to  be  used  as  a  preparing  vessel,  in 
which  to  treat  the  ore  with  chemicals. 

a  is  a  vat  furnished  with  a  stirrer  6,  and  a  false 
bottom  c,  which  forms  a  filter.  The  pulp  from  the 
battery  is  delivered  into  a  by  the  trough  d,  and  by 
the  action  of  the  stirrer  is  prevented  from  settling. 
The  water  passing  through  the  filter  c,  fills  the 
pipe  e,  the  lower  end  of  which  dips  into  a  vessel  of 
water  g.  The  cock  /,  being  now  opened,  a  sue- 


SILVER   ORES. 


103 


tion  is  established  through  the  pipe  by  the  weight 
of  the  column  of  water  within,  and  the  surplus 
water  in  the  pulp  is  rapidly  drawn  off,  the  flow 
from  the  battery  being  diverted  at  the  proper  time 
into  another  similar  machine.  "When  the  pulp  in 
a  is  of  the  proper  consistency,  the  cock/,  is  closed, 
the  plughole  h,  opened,  and  the  contents  of  the 

a 


vat  discharged  into  the  pan  i.  Previous  to  this, 
however,  the  pulp  in  a  may,  if  desired,  be  treated 
with  chemicals  and  steam,  to  prepare  it  for  amal- 
gamation. The  machine  may  of  course  be  geared 
from  Iclc'N  Ji 


104  TESTING   AND   WORKING 

In  large  mills  the  vat  or  tank  would  be  in  the 
usual  form,  with  two  or  more  stirrers,  as  shown  in 
Kg.  2. 

FIG.    2. 


Oj                 X./               o\  T 

v\ 

4-    CX 

fh 

a  is  a  row  of  four  batteries,  with  sluices  leading 
into  either  of  the  vats  b  b,  each  of  which  has  three 
stirrers,  c  c  c.  The  entire  bottom  of  each  vat,  ex- 
cept the  rests  for  the  stirrers,  is  a  filter,  and  each 
vat  holds  enough  pulp  to  charge  all  the  pans. 

The  vats  may  be  arranged  for  upward  filtration,  if 
desired,  as  in  Fig.  3,  in  which  the  letters  corres- 
pond with  those  in  Fig.  1. 

The  filter  c,  in  this  arrangement,  can  be  easily 
cleaned  if  it  should  become  choked,  as,  by  turning 
the  pipe  et  in  the  side  of  the  vat,  its  position  can 
be  reversed.  It  may  also  be  arranged  around  the 
sides  of  the  vat.  A  vat  with  a  stirrer  or  stirrers 
may  be  used  with  or  without  a  filter.  In  the  lat- 


SILVER   OBES. 


105 


ter  case,  the  stirrer  is  best  made  in  the  form  of  an 
obtuse  cone,  with  the  apex  downward,  thus,  X,  in 
order  that  it  may  easily  work  its  way  into  the  sedi- 
ment, and  it  is  arranged  to  be  raised  or  lowered  at 
pleasure ;  the  pulp  is  allowed  to  settle,  and  the 

FIG.  3. 


surplus  water  to  flow  out,  by  gates  or  plugs,  just 
as  in  the  common  ore  tank,  and  when  a  sufficient 
quantity  of  ore  has  entered,  the  incoming  stream 
of  pulp  is  stopped,  and  the  water  being  reduced 
by  the  plug-holes  to  the  required  quantity,  the 
stirrer  is  put  in  motion,  and  gradually  lowered  to 
5* 


106  TESTING   AND    WORKING 

stir  up  the  sediment,  so  that,  forming  with  the  wa- 
ter a  semi-liquid  mass,  or  pulp,  it  may  flow  through 
the  spout  h  into  the  amalgamator,  or  it  may  even 
be  ground  or  amalgamated  in  the  vessel  a,  if  said 
vessel  is  so  constructed  as  to  answer  these  pur- 
poses. 

[84.1  NOTE. — In  case  persons  desiring  to  use  di- 
chloride  of  copper  should  be  deterred  from  so  doing 
by  the  fact  of  a  patent  having  been  granted  on  the 
use  of  that  substance  "  in  barrels,  pans  or  tubs," 
and  which  patent  has  been  sold  to  certain  parties 
for  a  large  sum  of  money,  the  following  from  the 
Mining  and  Scientific  Press,  written  by  Dr.  Lansz- 
weert,  may  be  useful,  antedating,  as  it  does  by 
some  years,  and  therefore  invalidating,  the  patent: 

The  Problem  of  Gold  and  Silver  Extraction— A 
General  Review,    No,  16, 


BY  PEOF.  L.  LANSZWEERT. 


In  continuing  my  remarks  upon  silver  processes, 
the  last  of  which  appeared  in  your  issue  of  July 
29th,  I  would  say  that  in  the  Freiburg  process,  it 


SILVER   ORES.  107 

is  of  the  utmost  importance  that  no  free  proto- 
chloride  of  copper  should  be  present  in  the  reduc- 
tion of  silver  ores,  as  by  giving  up  to  the  mercury 
one-half  of  its  chlorine,  a  considerable  loss  of 
that  metal  is  produced  by  chemical  reaction. 
When  this  does  occur,  lime  is  added  for  the  pur- 
pose of  decomposing  the  excess  of  chloride  of 
copper,  and  its  prejudicial  action  on  the  mercury 
is  arrested. 

USE  OF  BICHLORIDE  OF  COPPER  IN  THE  PAN  PROCESS. 

To  avoid  this  loss,  which,  at  the  end  of  the  year 
forms  a  considerable  item  in  the  expenses  of  a 
mill,  and  to  facilitate  a  more  direct  and  easy  de- 
composition of  the  sulphurets  of  silver  in  the 
Washoe  ores  (admitting  the  rationale  of  the  theory 
of  the  patio  process  as  explained  in  my  last  num- 
ber), I  availed  myself,  during  my  stay  in  Washoe, 
of  the  opportunity  to  try  the  direct  use  of  dichlo- 
ride  of  copper  (cu  2  cl.)  on  the  different  ores  there 
presented.  The  success  realized  quite  surpassed 
my  expectations.  The  results  were  obtained  by 
comparative  experiments  made  on  a  large  scale, 
by  reducing  from  five  to  five  hundred  tons  of  the 


108  TESTING  AND   WOBKING 

various  Washoe  ores,  such  as  Gould  &  Curry  No. 
2,  Chollar,  Potosi,  Olney,  Bogers,  Gold  Hill,  etc., 
and  were  attested  by  certificates  from  Guido  Kus- 
tel,  Col.  Breevort,  Mr.  Lambert,  J.  Corey,  Joseph 
Trench  and  others,  as  the  experiments  were  con- 
ducted at  their  several  mills.  They  averaged,  ac- 
cording to  the  nature  of  the  ores,  from  within  five 
to  twenty  per  cent,  of  the  assay  value  of  the  ores. 

The  quantity  of  dichloride  of  copper  used  was 
based  on  the  analysis  of  the  ores,  and  the  percent- 
age of  the  sulphide  of  silver  they  contained. 
Taking,  for  example,  an  ore  assaying  $100  per  ton, 
we  would  have,  according  to  analysis,  sixty -two 
ounces  of  sulphide  of  silver,  equal  to  fifty-four 
ounces  of  metallic  silver,  at  $1.29  per  ounce^ 
which  is  worth  $70,  and  free  silver  at  $30  —  $100. 

The  patio  process  requires  for  the  reduction  of 
the  above  amount  of  sulphide  of  silver  125  ounces 
of  sulphate  of  copper,  590  ounces  of  salt,  and  100 
ounces  of  mercury ;  the  mercury  being  lost  by  de- 
composition as  a  chloride  of  mercury — the  calomel 
of  the  apothecary. 

Now,  if  we  use,  instead  of  the  above,  the  dichlo- 
ride of  copper,  47  ounces  (the  quantity  required 
for  the  reduction  for  the  amount  of  sulphide  of 


SILVER   ORES.  109 

jr>  '      y,  '    „•/ 

silver  present),  plus  400  ounces  of  salt  and  100 
ounces  of  mercury,  there  will  be  no  loss  of  the 
mercury. 

In  nearly  all  enterprises  of  this  kind  a  great 
many  obstacles  are  thrown  in  the  way  of  success, 
by  reason  of  the  stubbornness,  incapacity  or  avidity 
of  those  having  charge  of  the  different  works.  So 
in  this  case;  notwithstanding  the  proof  was  abun- 
dant of  more  favorable  results  than  were  being  ob- 
tained by  the  old  processes,  still  such  was  the  sys- 
tematic opposition  presented  by  superintendents, 
amalgamators  and  others  interested  in  retaining 
present  positions,  or  in  continuing  the  use  of  other 
processes,  the  writer  found  it  impossible  to  intro- 
duce his  process  into  permanent  use  in  any  of  the 
numerous  mills  in  Washoe.  Time  and  circum- 
stances will  eventually  accomplish  for  the  mining 
interest  of  that  locality,  what  the  stubbornness  or 
incapacity  of  the  early  operators  there  refused  to 
allow;  although  thousands  of  dollars  might  there- 
by have  been  saved  to  individual  companies  alone. 

Although  the  preparation  of  dichloride  of  cop- 
per is  very  easy  and  simple,  still  a  great  many  at- 
tempts to  prepare  it  have  failed;  the  operators  pre- 
paring instead,  a  mixture  containing  a  large  per- 


110  TESTING   AND   WORKING 

centage  of  protochloride  and  very  little  dichloride 
of  copper;  and  being  in  consequence  disappointed 
in  the  results  from  the  use  of  this  preparation,  they 
have  condemned  a  process  which  my  own  careful 
experiments  on  a  working  scale  have  proven  to  be 
the  best  yet  adopted  for  the  reduction,  without 
roasting,  of  a  certain  class  of  Washoe  ores. 


TABLE  OF  CONTENTS. 


TESTING  OEES  FOE  SILVEB. 
Subject.  Section.  Page. 

Kock  Formation 1  7 

Test  for  Silver 2  8 

Silver,  Indication  of  Presence 3  10 

Silver  Test  with  Heat  and  Water 4  11 

Silver  Test  with  Nitric  Acid 5  12 

Silver  Test  with  Blow-pipe 6  13 

TESTING  FOB  A  PBOOESS. 

Extent  and  Kichness  of  Ore 7  14 

Smelting  Ores 8  15 

Selecting  Sample 9  16 

Working  Sample 10  16 

Copper  Test 11  18 

Bluestone 12  19 

Appliances  for  Testing 13  20 

Boasting 14  21 

WOBKING  OBES. 

Aaron's  Process 15  23 

Superheated  Steam 18  25 


112  TABLE   OF   CONTENTS. 

Subject.                                                                          Section.  Page. 

Dichloride  of  Copper,  Preparation 19  26 

Protochloride  of  Copper 20  26 

Carbonate  of  Copper  Ores 21  27 

Use  of  Copper  and  Iron 22  29 

Quantity  of  Chemicals 23  29 

Carbonate  of  Lime -.*     ...    24  30 

Class  of  Ores  Worked  by  Aaron's  Process 25  30 

Chloride  Ores 26  30 

Amalgam 27  31 

Patchen's  Process 28  33 

BOASTED  OBES. 

Working  Eoasted  Ores 29  34 

Base  Metals 30  35 

Chloridizing  Boasting 31  36 

Directions  for  Boasting 32  37 

Stirring 36  40 

Heat 37  40 

Want  of  Sulphur 38  41 

LEACHING  PEOCESSES. 

Classes  of  Leaching  Processes 39  41 

Smelting 40  42 

Mexican  Process 42  43 

Kroencke's  Process 43  44 

'Chilian  Process 44  48 


TABLE    OF    CONTENTS.  113 

* 

PULVERIZING  MACHINES. 
Subject.  Section.  Page. 

Arrastra 46  49 

Operation  of  Arrastra . , 47  50 

FeedandSpeed + 48  51 

Dry  Grinding  of  Arrastra 49  52 

Stamp  Batteries 50  53 

Screens 51  53 

Crocker's  Trip  Hammer  Battery 52  55 

Paul's  Pulverizing  Barrel 53  57 

Pulverizing  Barrel 54  60 

Kendall's  Battery 55  61 

Noice's  Pulverizer 56  61 

Cheap  Rock  Breaker 57  63 

AMALGAMATOBS. 

Cheap  Amalgamator 58  65 

Grinding  the  Ore 59  67 

Directions  for  Making  a  Barrel 60  68 

Copper 61  71 

Preventing  Mechanical  Wear 62  71 

Using  Quicksilver 63  72 

Copper  in  Bars 64  73 

Freiberg  Barrel 65  73 

Cheap  Barrel 66  74 

Trough 67  77 

Barrel  on  Kollers 68  79 

Aaron's  Amalgamator 69  79 

Separator 70  83 


114  TABLE   OF    CONTENTS. 

EETOETS. 

Subject.                                                                             Section.  Page. 

Improvised  Ketort 71  86 

Boasting  Furnace 72  88 

Furnace  Tools 72  88 

Furnace  Building 73  90 

{Smaller  Furnace , 74  91 

MISCELLANEOUS. 

Aaron's  Leaching  Apparatus 75  92 

Another  Arrangement 76  93 

Apparatus  No.  2 78  96 

A  Small  Mill 81  99 

Sampling  Tailings 82  101 

Settling  Tanks  83  102 

Bichloride  of  Copper 84  106 


ADVERTISEMENT. 


THE     CALIFORNIA 
ZFO"WID:Ei:R,  "VSTOIR/IKS, 

W 


Santa  Cm  GIIOI fe 


s 

cb 


o 

Pn 


00 


w 

Pacific  Rifle  and  Pistol  Powder,         ^ 

SHOT,  ROUND  GRAIN, 

CAPS,  BRIGHT   GLAZE, 

WADS,  IN    IRON    AND 

AMMUNITION,  WOODEN  KEGS,  FUSE,  ETC.,  ETC. 


No.  314  CALIFORNIA  STREET, 

SAN    FRANCISCO,  CAL. 


ADVERTISEMENT. 


WHITE'S     PATENT 
Revolving    Cylinder    Furnace 

— FOB— 

ROASTING     ORES. 


This  Furnace  was  patented  first  in  1864,  and  subsequently  in  1865,  covering 
any  arrangement  of  an  incline  cylinder  furnace.  It  consists  of  an  iron  cylinder 
mounted  upon  bearing  drums  or  wheels  at  a  suitable  inclination,  with  a  fire- 
place at  either  the  upper  or  lower  end  of  the  cylinder  as  desired.  The  cylinder 
is  revolved  by  suitable  power,  and  the  ore  is  fed  into  the  upper  end  of  the  cyl- 
inder continuously,  and  passes  through  its  entire  length. 

During  its  passage  the  ore  is  raised  by  projections  on  the  inside  of  the  cylinder 
and  allowed  to  drop  through  the  passing  heat,  thus  completely  roasting  it. 
The  operation  is  continuous  and  requi.es  but  comparatively  little  skill  and  at- 
tention in  working.  It  is  s'rnply  constructed  in  sections,  easily  transported, 
and  can  be  moved  and  reset  at  moderate  cost.  After  thorough  trial  it  is  found 
to  reduce  a  large  variety  of  ores  economically,  and  is  now  superseding  fur- 
naces of  perhaps  greater,  but  briefer  notoriety. 

Favorable  terms  will  be  offered  to  purchasers.  Address  for  further  informa- 
tion, 

OEO.    W.    WHITE, 

Care  of  Etna  Foundry,  Fremont  Street,  near  Folsom,  8.  F. 


NOTICE  TO  PARTIES  ORDERING  FURNACES.— The  mining  public  is 
hereby  notified  that  all  persons  who  represtnt  themselves  to  be  my  agents  or  to 
have  authority  under  my  patents  to  build  and  use,  or  to  contract  with  others 
for  the  light  to  build  and  use  a  Cylindrical  Rotary  Roasting  Furnace  (except  in 
Lander  county,  Nevada,)  are  frauds,  and  any  person  or  persons  that  constructs 
one  of  my  furnaces  either  with  or  without  additions,  alterations,  or  supposed 
improvements,  or  attempts  to  use  one  constructed  under  a  contract  with  any 
such,  unauthorized  person,  will  be  prosecuted  as  infringers  of  my  rights  on 
the  premises.  I  have  made  arrangements  to  have  all  my  furnaces  constructed 
by  the  Etna  Iron  Works  in  this  city,  and  no  other  foundry  has  a  right  to  make 
one  without  my  written  consent.  For  rights  to  build  and  use,  address 

<JEO.  W.  WHITE,  Patentee,  care  of  Etna  Iron  Works. 

San  Francisco,  Aug.  22d,  1876. 


ADVERTISEMENT,  iii 

/ETNA   IRON  WORKS, 

Fremont  St.,  Bet.  Howard  and  Folsom,        San  Francisco. 
PENDE 'ROAST  &  SMITH,  Proprietors. 

Manufacturers  of 
IKON    CASTINGS  &  MACHINERY    OP    ALL  KINDS. 

nartz    Mill 

AND  OTHEB 

MINING    MACHINERY 

A  SPECIALTY. 


The  Proprietors  of  these  works  have  been  long  established  in 
the  business,  are  practical  machinists  and  foundrymen,  who  know 
well  the  wants  of  customers  ia  their  line  of  business,  and  are  pre- 
pared to  give  the  fullest  satisfaction  in  all  particulars. 

They  have  a  full  complement  of  tools  in  perfect  order,  handled 
by  superior  workmen. 

Drawings  and  patterns  of  the  best  and  most  approved  mining 
machinery  are  at  the  service  of  the  patrons  of  this  foundry. 

Miners,  mill-men  and  metallurgists  are  invited  to  send  for  es- 
timates or  any  desired  information. 

THOS.  PENDERGAST.  HENRY  S.  SMITH. 


iv 


ADVEBTISEMENT. 


W.    T.    C  APR  ATT, 

Manufacturer  of 

Hooker's  Celebrated  Steam  Pump, 


The  best  cheap- 
est  and  most 

reliable 
STEAM  PUMP 

KNOWN. 

Over  3  000 
In  use  on  the 

Pacific  Coast, 

Giving  entire 

SATISFACTION. 


IMPORTER     OF 


Iron   Pipe    and  Malleable    Iron   Fittings. 
Brass   and   Bell   Foundry, 

CHURCH, 

Steamboat 

BELLS  &  GONGS, 

WATER  GAUGES, 
STEAM      GAUGES, 


Steam  Whistl  s, 
Engineers' 

Findings. 

CORNER    FREMONT   &    NATOMA    STREETS, 
SAN   FKANCISCO. 


Hydraulic  Pipes 

AND 

NOZZLES 

For  Mining  Parpo. 

sea,  and  a 

GENERAL 

ASSORTMENT  OP 

•  BRASS  WORK. 


ADVERTISEMENT. 


HENDY'S 

ORE    FEEDER. 

— o— 

Diagram  Showing  Plan  of 
Attaching  Feeder  to  Battery. 
Attacked  to  the  second  stamp 

A— Tappet.  B— Lever.  C— 
Lower  Guide.  D— Hopper. 
E— Carrier  Table.  F— 
Chut  =«.  Q— Bumper. 

JOSHUA~HENDY, 

No,   32  FREMONT  ST.,  S.  F. 
Patent 

Ore  Concentrators, 

BATTERY  ORE  FEEDERS, 


!  IIIIIJIIIIIIIIHlIi 


CIRCULAR  SAW  MILLS, 
Machinists'  Tools. 

Dealer  in  all  kinds  of   Ma- 
chinery. 

Steam  Engine  Governors. 

8^"  Send  for    Illustrated 
Circulars. 


ADVERTISEMENT. 


DEWEY    &   CO. 

U.  8.  and  Foreign 

Paleni  Agenls, 

No.  224  Sansome  St. 
San  Francisco. 


Patents  Obtained 
Promptly. 

Caveats  Filed  Expe- 
ditiously. 

Patent  Reissues  Ta- 
ken Out. 

Patents  Secured  in 
Foreign  Lands. 

Assignments  Made 
and  Recorded  in  Le- 
gal Form. 

Copies  of  Patents  and 
Assignments  Pro- 
cured. 

Examinations  of  Pat- 
ents made  here  and 
at  Washington. 

Examinations  Order- 
ed and  Reported  by 
TELEGRAPH. 

Examinations  msde  of 
Assignments  Record- 
ed in  Washington. 

Interferences  Prose- 
cuted. 

Opinions  Rendered  re- 
garding the  Validi- 
ty of  Patents  and 
Assignments. 

Rejected  Cases  taken 
up  and  Patents  Ob- 
tained. 

Every  Legitimate 
Branch    of    Patent 
Soliciting.       • 
Business    promptly 

and  thoroughly    con- 

ducted.    Send  for  Cir- 
cular. 

A.  T.  DEWEY, 
W.  B.  EWER, 
OEO.  H.  STRONG, 
JNO.  L  BOONE. 


Mining   and  Scientific  Press, 

Started  in  1860,  is  one  of  the  oldest  weekly  journals  now 
published  in  San  Francisco.  It  has  been  conducted 
by  its  present  proprietors  for  13  years,  during  which 
period  it  has  been  repeatedly  enlarged  and  constantly 
Improved.  The  active  and  steadfast  efforts  of  its  pub. 
lishers  have  gained  for  its  conduct  an  amount  of  practi- 
cal experience  greater  than  any  other  publishers  have 
accumulated  on  this  coast,  of  a  weekly  journal. 

The  sum  paid  by  us  for  the  best  editorial  talent  ob- 
tainable for  our  special  class  journal;  for  engravings, 
for  interesting  news  and  correspondence,  and  for  print- 
ing  a  large-sized,  handsome  sheet,  is  unequalled  by  that 
of  any  other  American  weekly  west  of  the  Mississippi. 
As  a  PBACTICAL  MINING  JOURNAL  it  has  no  rival  on 
this  Continent. 

It  is  the  only  MECHANICAL,  and  the  only  SonamFio 
Journal  of  the  Pacific  States. 
Miners,  Assayers,  Millman,  and  Metallurgist   in  the 

United  States  should  take  it. 

Pacific  Coast  Mechanics,  Engineers,  Inventors,  Manu- 
facturers, Professional  Men,  and  Progressive  and 
Industrial  Students  should  patronize  its  columns  of 
fresh  and  valuable  information. 

SCning  Engineers,  Superintendents,  Metallurgists,  Mine 
Owners  and  Mine  Workers  throughout  the  world 
should  profit  by  its  illustrations  a  d  descriptions 
of  New  Machinery,  Processes,  Discoveries  and 
Record  of  Mining  Events. 

Intelligent  thinkers  throughout  the  land,  in  high  or 
humble  situation,  who  would  avoid  literary  trash 
for  genuine  information,  should  SUBSCRIBE  AT 
ONCE.  Postage  paid,  H  a  year.  Send  for  sam- 
ple copy. 

DEWEY  &  CO.,  Publishers,  S.F. 

N.  B.— Valuable  books  on  Mining,  Metallurgy,  etc., 
published  and  sold.    Send  for  circulars. 


UNIVERSITY  OF  CALIFORNIA  LIBRARY, 
BERKELEY 


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